Migrate idd-comment spectra-bridge state onto .claude/.idd/state/bridge.json (config-protocol relocates it; idd-comment still uses old path)

[kiki830621]

Problem

Surfaced during /idd-verify of PR #198 (the #194/#195/#196 cluster), as an out-of-scope adjacent finding to the #195 config-path migration.

config-protocol.md (lines 137-139) ships a migration command that relocates the spectra-bridge state to the new .claude/.idd/ namespace:

[ -f .claude/state/idd-bridge.json ] && \
  mkdir -p .claude/.idd/state && \
  mv .claude/state/idd-bridge.json .claude/.idd/state/bridge.json

But idd-comment (and the canonical rules/spectra-bridge.md) still read and write the OLD location .claude/state/idd-bridge.json:

• read: skills/idd-comment/SKILL.md L124-125 (Step 0.7 detect_spectra_context)
• write: L368-369 (mkdir -p .claude/state + cat > .claude/state/idd-bridge.json, Step 7 spectra_bridge_resume) + L400 report line
• the rule rules/spectra-bridge.md documents the old path

So a user who has run config-protocol's migration (bridge state moved to .claude/.idd/state/bridge.json) → idd-comment's Step 0.7 detect won't find it → the spectra-discuss ↔ idd-comment bridge resume silently breaks.

This is the same class as #195 (incomplete namespace migration) but for bridge-state, not the local.json config — explicitly left out of #195's scope.

Proposed fix

Migrate idd-comment's bridge-state read + write onto .claude/.idd/state/bridge.json (new-path-first on read with legacy fallback; mkdir -p .claude/.idd/state on write), and update rules/spectra-bridge.md to specify the new location. Keep reading the legacy .claude/state/idd-bridge.json as fallback for backward compat (mirrors the #195 reader pattern).

Severity

LOW — only bites users who ran the config-protocol migration AND use the spectra-discuss ↔ idd-comment bridge-resume flow.

Refs #195 (sibling namespace migration; this is the bridge-state counterpart).