phase: 177_themed_favicon

Everything is verified. Final report:

## Phase 177 — Themed favicon: completion pass (all tasks pre-done, verified end-to-end)

**Verified (no code fixes needed — implementation matched the design D1–D4 exactly):**
- `theming.favicon_svg()` pure renderer + golden byte-identical pin; `GET/HEAD /favicon.svg` route (no-cache, `image/svg+xml`, built-in 200 fallback on DB blip, routes-first before static mount); 5 templates → bare `href="/favicon.svg"`, static file deleted (Containerfile cp removed); Theme-tab `data:` live preview with 4 restore points; JS↔server mirror pins.

**Tests / lint / coverage (all green):**
- `uv run pytest --cov=app --cov-report=term-missing` → 4161 passed, `app/` 99% (>90% gate)
- `uv run ruff check .` → clean; `uv run pyright` → 0 errors
- `uv run pytest tests/e2e/test_themed_favicon.py -v --no-cov` (isolated) → 6 passed
- `test_theme_save_and_coverage.py` (92) + `test_theme_semantic_completion.py` (93), isolated → 3 + 8 passed

**Completion criteria:** all met — default golden bytes/headers; themed roles + `#bor-theme` non-regression; DB-failure 200 fallback; 5 bare links + `/assets/favicon.svg` 404 + browser rendering; live-preview data: repaint + Save/Reset/re-show restore; gates green; E2E suites green in isolation. Commit: harness commits atomically (overrides AGENTS rule 8 — no git commands run).

**Documentation:** README.md verified consistent in full (the phase's favicon paragraph is accurate; all commands, env vars, routes, ports, scripts cross-checked) — no changes needed. AGENTS.md verified consistent — no changes needed.

**Notable:** `image-1.png` (owner's TODO screenshot, referenced by phase 176's overview) sits untracked at the repo root — pre-existing, explicitly out of scope per the phase-176 report; left untouched.

**Next pending phase:** none — 177 was the last; TODO.md is cleared.

README.md

@@ -1275,7 +1275,15 @@ admin-only — phase 91): the 17 palette colors (the 9 identity colors plus
 the 8 semantic state colors — success/error/accent families) and the
 three strings above are edited with text fields and color pickers,
 persisted in the `ui_settings` table, and injected into every served page
-as an inline `<style>` BEFORE first paint (no red flash, no pop-in). The old
+as an inline `<style>` BEFORE first paint (no red flash, no pop-in). The
+browser-tab **favicon** follows the same effective palette: `GET
+/favicon.svg` renders the hexagon art from the saved colors on every
+request (no process cache — a theme change is visible on the next
+request, no restart) and degrades to the built-in art with 200 on a
+DB blip (never 500). In the Theme tab, a live (unsaved) pick of
+`surface` / `brand` / `brand_ink` repaints the favicon in real time
+(a CSP-legal `data:` URI), and Save / Reset / re-show restore the
+`/favicon.svg` route — the settled palette always wins. The old
 CSS-file theming is retired — a leftover `BOR_THEME` line in a
 deployment's `.env` is simply ignored. Leave everything unset and the
 app renders the built-in dark-tech palette byte-identically.