Decompose implementation review fixes into 14 atomic tasks with post-fix review

Break down findings from review #002 into dependency-ordered fix tasks:

Critical/High:
- fix/acme-contact-and-challenge (C1+C2): Add acme_contact field, wire to
  ACME, remove unused challenge_config, add validation rule 19
- fix/remove-health-and-hardcode-https (W5+W14+ADR-022): Remove /health
  from main listener, hardcode X-Forwarded-Proto to https
- fix/config-reload-static-drift (C4): Use ArcSwap<StaticConfig> so reload
  diffs against last config, not startup config
- fix/access-logging (W13): Wire up log_request! macro for every proxied
  request with client_ip, host, method, path, status, upstream, duration_ms

Medium:
- fix/graceful-shutdown (W1+W7): Join HTTPS tasks with timeout instead of
  abort, add shutdown signal to admin socket and eviction task
- fix/connect-timeout (W4): Wire upstream_connect_timeout_secs to enforce
  separate connect timeout

Low/Independent:
- fix/token-bucket-nanosecond (W6): Use as_nanos() instead of as_millis()
- fix/normalize-host-ipv6 (S3): Handle IPv6 bracket notation in normalize_host
- fix/http-port-validation (S1): Validate http_port in range 0 or 1-65535
- fix/integration-test-toml (S10): Fix double-nested listeners.listeners.sites
- fix/logging-test-global-subscriber (W9): Use try_init() to avoid test conflicts
- fix/fragile-error-detection (W3): Add typed error matching or documented string match
- fix/add-code-comments (C3,W8,W10,W11,S9): Document correct-but-non-obvious behaviors
- fix/request-timeout-scope (S8): Document full-request timeout scope
- fix/clean-dead-code (S4+S2): Remove dead_code annotations, add #[non_exhaustive]

Review gate:
- review/post-fix-review: Verify all fixes against architecture spec

tasks/fix/normalize-host-ipv6.md

@@ -0,0 +1,58 @@
+---
+id: fix/normalize-host-ipv6
+name: Fix normalize_host to handle IPv6 bracket notation
+status: pending
+depends_on: []
+scope: single
+risk: low
+impact: isolated
+level: implementation
+review_findings: [S3]
+---
+
+## Description
+
+`normalize_host` in `src/config/dynamic_config.rs` uses `split(':').next()` to strip ports, but this fails for IPv6 addresses in brackets (e.g., `[::1]:443` would normalize to `[::1]` instead of `::1`). The `strip_port_from_host` function in `src/tls/redirect.rs` correctly handles this case.
+
+### Changes Required
+
+**`src/config/dynamic_config.rs`**:
+- Replace the `normalize_host` implementation with a port-stripping function that handles IPv6 bracket notation
+- Either extract a shared utility function from `strip_port_from_host` in `redirect.rs`, or make `normalize_host` use the same logic
+- The function should:
+  - If host starts with `[`, find the closing `]` and strip the port after it
+  - Otherwise, use the existing `split(':').next()` logic
+  - Convert to lowercase
+
+**`src/tls/redirect.rs`**:
+- Consider extracting `strip_port_from_host` into a shared module (e.g., `src/utils.rs` or inline in both places) to avoid code duplication
+
+### Tests
+
+- Add test cases for `normalize_host` with IPv6:
+  - `[::1]:443` → `::1` (or `[::1]` depending on convention — check what the routing table expects)
+  - `[2001:db8::1]:8080` → `2001:db8::1`
+  - Plain hostname with port: `example.com:443` → `example.com`
+  - Plain hostname without port: `example.com` → `example.com`
+
+## Acceptance Criteria
+
+- [ ] `normalize_host` correctly strips ports from IPv6 bracket notation
+- [ ] Either a shared utility function is extracted, or both implementations use the same logic
+- [ ] New test cases for IPv6 host normalization
+- [ ] Existing routing tests pass
+- [ ] `cargo clippy` passes with no warnings
+
+## References
+
+- docs/reviews/002-implementation-review.md — S3 finding
+- src/config/dynamic_config.rs — `normalize_host` function
+- src/tls/redirect.rs — `strip_port_from_host` function (correct implementation)
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion