feat(server): serve the client-only build with Bun

Angular's server build needs Node loader hooks that Bun does not apply,
and every route is client-rendered, so Angular now builds a client-only
bundle and a small Bun.serve server delivers it: hashed assets with the
one-year cache, index.html revalidated, extension-less routes falling
back to index.html, missing assets 404, traversal and malformed paths
rejected, and other methods 405. Express, @angular/ssr and the unused
hydration provider are removed. Both Docker stages use the pinned
oven/bun:1.4.3-alpine image without Node, and the health checks use
Bun's fetch.

Refs #292

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/trace-free-planning-verification.md

@@ -21,8 +21,7 @@ benchmark inputs, CI settings or performance limits.
 | Benchmark callers | Supported calculation outcome, explanation and timings; no trace promises, waits, counts or replacement trace metrics. |
 
 Production-source searches found no decision-trace, historical analysis,
-acknowledgement or replay implementation. Angular hydration's `withEventReplay`
-is unrelated to planning history. `PlanningArtifacts` carries actual explanation,
+acknowledgement or replay implementation. `PlanningArtifacts` carries actual explanation,
 final-state and planning-work timing data, rather than a compatibility shell.
 
 ## Existing deterministic fixtures