feat(entry-points): canonical build-mios.{sh,ps1} naming + 3-min auto-accept

Renamed the Windows build orchestrator and consolidated the user-facing
entry-point naming convention:

  mios.git
    mios-build-local.ps1  -> build-mios.ps1            (renamed)
    mios-build-local.ps1                               (now a redirector)

  mios-bootstrap.git
    install.sh            -> build-mios.sh             (renamed)
    install.ps1           -> build-mios.ps1            (renamed)
    install.sh            (now a redirector)
    install.ps1           (now a redirector)
    bootstrap.sh          (already a redirector; banner refreshed)

Why: 'build-mios.<platform-extension>' is the single, predictable name
across both repos and both platforms. The four old entry-point names
(mios-build-local.ps1, install.sh, install.ps1, bootstrap.sh) are kept
as one-shot redirector stubs so existing curl|bash and irm|iex
one-liners, shortcuts, and CI pipelines that point at the old URLs
keep working without any user-side change.

3-MINUTE AUTO-ACCEPT TIMEOUT (PowerShell + bash)
================================================
Read-Timed (build-mios.ps1) gains a -TimeoutSec parameter (default 180s
= 3 minutes; honors $env:MIOS_PROMPT_TIMEOUT; -le 0 means wait
forever). Previously it referenced an undefined $Timeout variable --
that's now closed. When the timer fires the resolved default is taken
silently and a '(auto-accept after Ns)' note is printed so the unattended
choice is auditable.

prompt_default (build-mios.sh) wraps 'read -r' with '-t
${MIOS_PROMPT_TIMEOUT:-180}'. On EOF or timeout, the resolved default
is taken and a one-line note is emitted to stderr so the install log
captures the unattended decision. Set MIOS_PROMPT_TIMEOUT=0 to disable
(wait forever); MIOS_PROMPT_TIMEOUT=1 in CI for fastest unattended
runs.

The defaults the timeout falls back to are the ones already resolved
from the unified mios.toml chain (vendor / host / per-user) by
tools/lib/userenv.sh -- so the 'global MiOS/mios defaults' the
3-minute clause refers to are exactly the values an operator could
have set in mios-bootstrap.git/mios.toml before kicking off the build.

DOCS / ALLOW-LISTS
==================
- AGREEMENTS.md section 4 entry-point table updated to list build-mios.*
  as canonical, with the old names noted as redirectors.
- .gitignore in both repos: whitelist /build-mios.{sh,ps1}; old
  whitelist lines kept so the redirector stubs stay tracked.
- Banner messages in the renamed scripts now report 'build-mios.{sh,ps1}'
  rather than the old name.

The renamed-with-redirector layout means existing one-liner URLs
(.../install.ps1, .../bootstrap.sh) continue to land on functional
scripts; the old scripts immediately exec the new build-mios.<ext>
sibling (or fall back to fetching it from raw.githubusercontent.com
when the script was curl|bash-piped without an on-disk neighbor).

Author: Kabuki94

.gitignore

@@ -60,6 +60,7 @@
 !/install-mios-agents.sh
 !/Get-MiOS.ps1
 !/install.ps1
+!/build-mios.ps1
 !/mios-build-local.ps1
 !/preflight.ps1
 !/preflight.sh

AGREEMENTS.md

@@ -77,13 +77,12 @@ referencing this file when it starts.
 |---|---|---|
 | `just <target>` | mios.git | All build orchestrator targets (`build`, `iso`, `qcow2`, `vhdx`, `wsl2`, `rechunk`, `sbom`, `init-user-space`, `edit`, `show-env`, ...) |
 | `./preflight.sh`, `./preflight.ps1` | mios.git | Build prerequisite checks |
-| `./mios-build-local.ps1` | mios.git | Windows build orchestrator |
+| `./build-mios.ps1` | mios.git | Windows build orchestrator (formerly `mios-build-local.ps1`) |
 | `./push-to-github.ps1` | mios.git | GHCR push helper |
 | `./Get-MiOS.ps1` | mios.git | Image fetcher |
-| `./install.sh`, `./install.ps1` | mios.git | System-side installers |
+| `./install.sh`, `./install.ps1` | mios.git | System-side installers (Phase-3) |
 | `./install-mios-agents.sh` | mios.git | Agent-launcher installer |
-| `bash bootstrap.sh`, `bootstrap.ps1` | mios-bootstrap.git | Phase-0 bootstrappers |
-| `./install.sh`, `./install.ps1` | mios-bootstrap.git | User-facing installers |
+| `./build-mios.sh`, `./build-mios.ps1` | mios-bootstrap.git | Canonical user-facing entry points (formerly `install.{sh,ps1}` / `bootstrap.{sh,ps1}`; old names are now redirector stubs) |
 | `mios`, `mios-llm`, `mios-agent-claude`, `mios-agent-gemini` | deployed image | Runtime CLI surface |
 | `bootc upgrade`, `bootc switch ghcr.io/mios-dev/mios` | deployed image | OS lifecycle commands operating on a 'MiOS' image |