REUSE-WP-0018-T03: LLM semantic rerank for plan-check

llm-connect came up locally (mock provider, 127.0.0.1:8080), unblocking
this task.

reuse_surface/plan_check.py: build_rerank_prompt/request_rerank/apply_rerank,
reusing llm_bridge.execute_prompt/extract_json_object (same pattern as
maintain_llm.py's request_maintain_patches). New schema
schemas/plan-check-rerank.schema.json rejects malformed responses (missing
fields, non-JSON, invented candidate ids outside the input set) rather than
guessing.

Per design principle 3 (deterministic matches always rank first),
apply_rerank appends LLM-scored entries after the deterministic list
(kind: 'llm') instead of reordering it -- the trusted base result is
identical with or without the rerank pass. Graceful skip via a 'notes'
field when LLM_CONNECT_URL is unset or the response is malformed, mirroring
maintain.py's no_llm/skip pattern. New --llm-url/--no-llm CLI flags.

Also extended plan-check-result.schema.json for 'notes' and the
(pre-existing, previously unschema'd) 'filed_capability_request' field.

9 new pytest cases; 89 total pass. Live-verified against the running
llm-connect instance: it correctly rejected the mock provider's non-JSON
response and surfaced the skip note, with the deterministic verdict and
match order completely unaffected.

REUSE-WP-0018 is now fully done (T01-T06). Updated
docs/IntentScopeGapAnalysis.md priority 29 to Closed and the workplan's
own frontmatter status to finished.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

specs/PlanCheck.md

@@ -2,7 +2,8 @@
 
 **Repository:** `reuse-surface`
 **Artifact:** `specs/PlanCheck.md`
-**Status:** Draft 0.1 (REUSE-WP-0018-T01)
+**Status:** Implemented (T02 deterministic matching, T03 LLM rerank, T04
+State Hub bridge, T05 ecosystem convention, T06 docs/CI all shipped)
 **Schema:** `schemas/plan-check-result.schema.json`
 
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