fix(server): address PR #23 review — 4 critical bugs, 3 warnings, 11 suggestions

Critical fixes:
- Add PendingRecognitionWire serialization roundtrip test
- Check Option return from delay.cancel() before logging
- InputQueue capacity limit (1000) with drop-oldest and warning
- TODO in observation.rs references ticket #450

Warning fixes:
- Hot-reload guards against invalid/empty content root
- Location header mismatch warning in line pool indexing
- walk_yaml() depth limit (100) against symlink loops
- Consecutive reload failure counter (warns after 5+)

Test additions:
- Negative prerequisite filtering test for monologue lines
- Integration test for pending_recognitions in observer snapshot
- Eavesdrop threshold ordering assertion (Careful < default)

Documentation:
- Playtesting expectation comments on delay constants
- is_pending() scalability note for future NPC cognitive delay
- ID format regex validation in line pool spec
- BTreeMap vs sort() ordering clarification in loader
- Multiplayer TODO in relationships.rs references D-010
- ContentSlug ticket #452 filed for entity slug resolution

394 tests, 0 failures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/architecture/line-pool-format.md

@@ -336,6 +336,19 @@ lines:
 | `character` | single char | `s` = smuggler, `d` = detective. **Monologue only.** | `s`, `d` |
 | `sequence` | 3-digit zero-padded | `001`–`999` | `001`, `042` |
 
+**General validation regex** (matches both dialogue and monologue IDs):
+
+```
+^[a-z0-9-]+_(d|m)(_[a-z])?_\d{3}$
+```
+
+- `[a-z0-9-]+` — location slug (kebab-case, at least one character)
+- `(d|m)` — pool type: `d` for dialogue, `m` for monologue
+- `(_[a-z])?` — optional character segment (monologue only): `_s` or `_d`
+- `\d{3}` — three-digit zero-padded sequence number
+
+Use the pool-specific regexes in [Section 5.2](#52-regex-patterns) for strict per-type validation. This general regex is useful for quick format checks that accept either type.
+
 > **D-035 deviation note:** D-035 specifies `{template}_{d|m|e}_{###}`. This spec refines that to `{location-slug}_{d|m}_{###}` (dialogue) and `{location-slug}_m_{s|d}_{###}` (monologue) for two reasons: (1) location-slug is more precise than template name and matches the directory hierarchy, and (2) monologue IDs include a character segment (`s`/`d`) to ensure uniqueness across the hard character partition (D-032). All existing authored content already uses this refined format. D-035 should be updated to reflect the implemented convention.
 
 ### 5.2 Regex patterns