chore: release v1.0.0-alpha.12

[ZingerLittleBee]

Summary

Cut release v1.0.0-alpha.12 (previous: v1.0.0-alpha.11, 2026-07-03).

• Backfill [Unreleased] with the user-visible changes merged since alpha.11 that were missing from the changelog (fix: UI/UX audit fixes — capability honesty, clean errors, dashboard & alerts #146–feat(web): merge network quality detail into server detail tabs #158, fix(web): dashboard widget interaction, sizing, and config fixes #164, fix(agent): resolve host OS in docker mode #166, fix(web): cross-discipline UI review fixes for the primary flow #169), then condense the whole section to user-facing one-liners
• Rename [Unreleased] to [1.0.0-alpha.12] - 2026-08-03 and add a fresh empty [Unreleased]
• Bump Cargo.toml workspace version, apps/web/package.json, and regenerate Cargo.lock

Release highlights

• Added: Docker container lifecycle controls (start/stop/restart/remove from the detail dialog)
• Changed: network quality detail merged into the server detail page tabs
• Security: all WebSocket endpoints now authenticate through the shared HTTP credential policy
• Fixed: 32 web UI review fixes (a11y/layout/color/copy), dashboard widget resize and jitter fixes, capability changes resync immediately, temporary grants end cleanly, manual monitor checks follow the full check policy, last-admin race, GeoIP backfill, notification dialog dismissal, i18n leaks, ANSI-free agent logs, host OS detection in Docker

Full notes in CHANGELOG.md under [1.0.0-alpha.12].

After merge

Tag the merge commit as v1.0.0-alpha.12 (annotated) to trigger the release workflow.