feat: compose Web UI from ordinary plugins

[kachofugetsu09]

Summary

• publish a source-neutral Web module catalog and browser Host; Core owns only exact-snapshot resource validation, web.root.v1, mount, and cleanup
• compose the product recursively through ordinary plugins: shell-ui owns pages, workbench-ui owns panels, and models owns connection-type UI
• register conversation, workbench, runtime, models, OpenAI-compatible, Codex, OpenCode Go, Akasha, Wake, and installed panels through the same loader and lifecycle
• keep parent CSS inheritance aligned with the plugin tree while child modules own their domain layout and cleanup
• remove legacy Dashboard globals, duplicate model settings UI, dead CSS, duplicate artifacts, and React-component plugin ABI
• move Shell/Workbench/Akasha/Wake editable source and CSS into their plugin directories; every bundled panel now uses the same plugins/*/web/index.tsx discovery path, with no product-specific build list
• plugin builds now consume only plugin source plus the public @akashic/web-ui-v1 Tailwind preset

Core web.root.v1
└── shell-ui shell.pages.v1
    ├── conversation-ui
    ├── workbench-ui workbench.panels.v2
    │   └── Akasha / Wake / installed panel plugins
    ├── runtime-ui
    └── models models.connection-types.v1
        └── OpenAI-compatible / Codex / OpenCode Go

The cumulative diff is 156 files, 9,446 insertions, and 9,166 deletions. Frozen JS/CSS artifacts account for most generated churn; the final ownership cleanup moved shared Tailwind values into the public SDK, removed the last Host-specific residue, and deleted the separate Akasha/Wake build path.

Validation

• final Core HEAD: cc43da2da20445438ec55f0bb6e980d4c0b4ab0b
• Core CI: 8/8 checks passed on the final HEAD, including full pytest/Pyright, change-impact, restart, Docker control, passive composition, fleet, mobile, and plugin composition gates
• final local semantic Gate: 26/26 public scenarios passed
  • report: docker/debug/reports/change-gate/20260830-232319-c6567388
  • source digest: 4a0c568671559eeaa7e18a6481c89a3dc2671a226694e34d2926b5fd373ad09e
  • plan digest: 152762513345e83c00a5d56a348eb577374b9a4df9dbb5badf53a012fb949e09
• frontend typecheck, targeted ESLint, theme/model tests, Dashboard/Web-plugin production builds, package dry-run, and 115 plugin composition/Shell/package tests passed
• Akasha/Wake pre/post migration registration and disposer contracts matched; repeated Web builds produced identical hashes
• controlled browser E2E rendered the 15-module exact catalog, real Workbench panels and counts, Models connections/provider cards, Codex child dialog, and light/dark theme; no Shell state polling occurred
• all five companion plugin PRs passed their final-head contract and behavior CI

Review

A native Terra xhigh reviewer performed the final read-only orthogonality review. It verified ordinary-plugin ownership, generic Web entry discovery, the single mount -> disposer lifecycle, nested CSS ownership, and the public SDK boundary. Final verdict on cc43da2d: PASS, no P0/P1, mergeable. It found no remaining safe deletion in the migrated Akasha/Wake boundary.

Companion plugin PRs

• fix(web-ui): compose emotion panel through Workbench akashic-plugins/emotion#10 — 5d4ea41
• fix(web-ui): compose Fitbit panel through Workbench akashic-plugins/fitbit-mcp#10 — 3bc21b0
• fix(web-ui): compose Meme panel through Workbench akashic-plugins/meme#7 — 404494d
• fix(web-ui): compose Observe panel through Workbench akashic-plugins/observe#7 — 1fd8095
• fix(web-ui): compose proactive panel through Workbench akashic-plugins/proactive_feedback#11 — 7e80a07

All six PRs are intended to merge together. No PR was merged by this change.

Production

This cleanup is not deployed. Production remains on the previously released Core a3b7f82e0268d0d8fe57b253cf3d61fcc407a558; merge and deployment are separate operations.

Recovery

• Core pre-cleanup branch: backup/web-ui-before-contract-closeout-20260830
• pre-Akasha/Wake entry migration branch: backup/web-ui-before-akasha-wake-entry-20260830
• each external plugin worktree has the same named pre-cleanup backup branch
• existing production recovery point remains /srv/data/services/akashic/operator-backups/pre-web-ui-final-a3b7f82e-20260830T2002Z