refactor(bridges): collapse chat bridges into auto-discovered bridges/*.sh files (#77)

* refactor(bridges): collapse chat bridges into auto-discovered bridges/*.sh files

Closes #76.

Per-bridge logic was scattered across 4 files in 11 case statements
totaling ~2,500 LOC: lib/chat-bridge.sh (install dispatcher),
lib/chat-bridges.sh (registry + templates), upgrade.sh (per-bridge
sync/systemd/launchd update), lib/summary.sh (per-bridge restart/verify
hints). Adding a new bridge meant editing 3+ files and threading a new
arm through every case. The runtimes/ layer already solved this same
shape via runtimes/<name>.sh auto-discovery; bridges now adopt the
same pattern.

New layout:

  bridges/
  ├── _dispatch.sh       — auto-discover, bridge_load, bridge_call,
  │                        bridge_has_hook, install_chat_bridge,
  │                        BRIDGE_DETECTION_ORDER + shared helpers
  │                        (_resolve_node_bin_dir, _compose_path_value,
  │                        _merge_systemd_env_lines, _smart_update_systemd_unit,
  │                        _ensure_systemd_path_contains, _plist_string_after_key)
  ├── kimaki.sh          — install + sync_config + render_systemd/launchd
  ├── kimaki/            — kimaki-private assets (plugins, post-upgrade.sh,
  │                        skills-kill-list.txt) — moved from repo root
  ├── cc-connect.sh
  └── telegram.sh

Hook contract every bridge implements (see bridges/_dispatch.sh
docblock for the full list): bridge_install, bridge_systemd_units,
bridge_launchd_labels, bridge_binaries, bridge_display_name,
bridge_display_title, bridge_render_systemd, bridge_render_launchd,
bridge_sync_config, bridge_update_systemd, bridge_restart_cmd,
bridge_verify_cmd, bridge_logs_cmd, bridge_start_hint, bridge_stop_hint,
bridge_is_ready. Optional: bridge_update_launchd, bridge_vps_setup_block,
bridge_launchd_setup_block, bridge_vps_start_preamble,
bridge_verify_extra. Optional hooks are gated through bridge_has_hook
so a bridge omits any prose block it doesn't need (cc-connect has no
setup blocks because it has no token).

Dispatch model:

* bridge_load <name>     sources bridges/<name>.sh into the current
                         shell. Used after CHAT_BRIDGE is decided so
                         install/sync hooks can mutate parent globals
                         (KIMAKI_BIN, RESOLVED_KIMAKI_PLUGINS_DIR,
                         UPDATED_ITEMS) the same way the legacy code
                         did.
* bridge_call <n> <hook> sources <n> in a SUBSHELL and invokes hook.
                         Used for registry walks (detection,
                         multi-bridge metadata queries) where parent
                         state must not be clobbered.

Detection priority is preserved via BRIDGE_DETECTION_ORDER constant
in _dispatch.sh (kimaki > cc-connect > telegram), then alphabetical
filesystem order for any future bridges added without updating the
constant. Hosts that somehow have multiple bridges installed see the
same tie-break behaviour as before.

Consumers all simplified:

* setup.sh sources bridges/_dispatch.sh and calls install_chat_bridge.
  No more 'lib chat-bridge' source line.
* upgrade.sh phase 2 / phase 5 / phase 5a became 4-line wrappers that
  call bridge_sync_config / bridge_update_systemd / bridge_update_launchd
  on the loaded bridge. The 215-LOC _sync_kimaki_config body and the
  three _update_*_systemd functions moved into bridges/<name>.sh as
  bridge_sync_config / bridge_update_systemd. _smart_update_systemd_unit
  and friends moved to bridges/_dispatch.sh as shared helpers.
* lib/summary.sh _print_*_setup_block case statements became
  bridge_<setup_block> hook calls; _print_launchd_run_block no longer
  takes a bridge arg (uses the loaded bridge's metadata directly).
* upgrade.sh's _print_verify_block kimaki special case became an
  optional bridge_verify_extra hook.
* runtimes/opencode.sh kimaki plugin paths repointed to
  $SCRIPT_DIR/bridges/kimaki/plugins/.

Tests:

* tests/bridge-render.sh rewritten as a golden-file regression suite.
  Renders every (bridge × unit / launchd-label) combo through the new
  bridge_render_* hooks and diffs against committed fixtures under
  tests/__snapshots__/bridges/. Pre-refactor it diffed legacy install
  function output against the new generators in lib/chat-bridges.sh;
  both files are gone, so the test is now snapshot-based with a
  --update flag for refreshing fixtures intentionally. The committed
  snapshots were captured by running the legacy bridge_render_*
  generators with deterministic env values, so this PR is provably
  byte-equivalent to main.
* tests/path-helpers.sh source path updated (lib/chat-bridges.sh →
  bridges/_dispatch.sh). 11/11 assertions pass.
* tests/post-upgrade-restore.sh path updated for the moved
  kimaki/post-upgrade.sh.

Live-verified on intelligence-chubes4: ./upgrade.sh --dry-run --local
output is byte-identical to main modulo timestamps and script paths.
The 8 rendered template snapshots are byte-identical to legacy output.

Net delta: ~1594 LOC deleted across the four legacy files; ~1830 LOC
added across the four new bridges/ files. Roughly LOC-neutral but the
shape is dramatically different — adding a new bridge is now 'drop a
file in bridges/' (the promise the README already made for runtimes,
now actually delivered for bridges).

The kimaki-only --kimaki-only upgrade flag and --no-chat setup flag
are unchanged; the README and skills/upgrade-wp-coding-agents/SKILL.md
references to file paths got updated for the move.

## AI assistance
- **AI assistance:** Yes
- **Tool(s):** Claude Code (Sonnet 4.5)
- **Used for:** Drafted the bridges/_dispatch.sh dispatcher, mechanically
  moved per-bridge functions out of lib/chat-bridge.sh / lib/chat-bridges.sh
  / upgrade.sh / lib/summary.sh into bridges/<name>.sh, rewrote
  tests/bridge-render.sh as a snapshot harness, and live-verified the
  byte-equivalence diff against main on intelligence-chubes4. Chris
  reviewed the dispatch model + hook contract and ran the smoke tests.

* docs(upgrade): repoint stale _sync_kimaki_config comment at bridge_sync_config

* fix(tests): sanitize PATH + KIMAKI_BIN in bridge-render harness

The committed kimaki-systemd / kimaki-launchd snapshots were generated on
my dev machine, where `command -v node` and the kimaki shim at
/Users/chubes/.kimaki/bin/kimaki are reachable. `_resolve_node_bin_dir`
correctly followed both, baking /Users/chubes/.kimaki/bin into the
rendered Environment=PATH= line. CI runners (clean Linux, no kimaki shim,
no node on PATH) rendered without that segment and failed the diff.

Two-part fix:

1. tests/bridge-render.sh now exports PATH=/usr/bin:/bin at the top of
   the env-mock block, so `command -v node` and the shim-parsing fallback
   both miss on every machine. Snapshots become reproducible.

2. The two kimaki snapshots refreshed to drop the dev-machine path
   segment. Diff is purely the removal of /Users/chubes/.kimaki/bin
   from the PATH= line — no template logic changed.

CI red on PR #77, fixed here.

Author: chubes4

README.md

@@ -256,10 +256,10 @@ Local installs run as your current user — no root, no service user, no chown.
 
 The default chat bridge for OpenCode. On VPS, wp-coding-agents installs post-upgrade hooks that:
 
-- **Remove unwanted bundled skills** — Kimaki ships with skills for frameworks and tools that aren't relevant to WordPress agent workflows. The kill list (`kimaki/skills-kill-list.txt`) controls which skills are removed after each upgrade.
+- **Remove unwanted bundled skills** — Kimaki ships with skills for frameworks and tools that aren't relevant to WordPress agent workflows. The kill list (`bridges/kimaki/skills-kill-list.txt`) controls which skills are removed after each upgrade.
 - **Filter redundant context** — A plugin strips Kimaki's built-in memory injection and scheduling instructions from the agent context, since DM handles those concerns. Saves ~2,400 tokens per session.
 
-To customize the kill list, edit `kimaki/skills-kill-list.txt` before running setup, or edit `/opt/kimaki-config/skills-kill-list.txt` on the server after install.
+To customize the kill list, edit `bridges/kimaki/skills-kill-list.txt` before running setup, or edit `/opt/kimaki-config/skills-kill-list.txt` on the server after install.
 
 On local installs, Kimaki installs globally via npm but without a systemd service. Run it manually: