docs(04-02): close the D-14 bake-off — threshold met on the first run, lever None

- docs/SEARCH-QUALITY.md: the bake-off close record — corpus v1 (75 cases) x
  gazetteer v1 (30 entries), measured 2026-10-23T17:02Z via npm run search:corpus
  - top-1 66/68 (97.1%), top-3 68/68 (100.0%) >= 90% threshold
  - negatives refused 7/7, refusal margin 0.643 < 0.72 admission line
  - per-category table (landmark/abbreviation/glued/typo/alias all 100%)
  - escalation lever: None — met on first run; no abbreviations.ts row, no
    alias, no corpus edit; the fixed ladder was never climbed
  - coordinate verification: 10 seed entries spot-checked against Nominatim
    (identifying UA, 1 req/s): 8/10 within 0.01°; bukit-bintang outlier is an
    area-vs-point discrepancy (no change); pavilion-kl was a real ~2 km error
  - both top-1 misses documented as expected disjoint-tier behaviour
- kl-gazetteer.json: pavilion-kl coordinate corrected (3.1478,101.695) ->
  (3.149,101.7132) — Rule 1 data bug found by the prescribed Nominatim
  verification; post-fix delta 0.0002°; corpus is coordinate-blind, all suites green

docs/SEARCH-QUALITY.md

@@ -0,0 +1,99 @@
+# Search quality — Phase 4 bake-off close
+
+**Corpus:** `search/test/fixtures/golden-corpus.json` version 1 — 75 hand-written cases
+(68 positive / 7 negative)
+**Gazetteer:** `search/src/data/kl-gazetteer.json` version 1 — 30 entries
+**Measured:** 2026-10-23T17:02Z via `npm run search:corpus`
+
+| Metric | Value | Threshold |
+|---|---|---|
+| top-1 hit rate (positives) | 66/68 (97.1%) | — (reported) |
+| top-3 hit rate (positives) | 68/68 (100.0%) | >= 90% |
+| negatives refused | 7/7 | 100% (zero leaks) |
+| refusal margin | best negative sim 0.643 < 0.72 | every negative strictly below `FUZZY_ADMIT_SIMILARITY` |
+| cost | 1.07 ms/query | 10 ms Workers Free CPU budget |
+
+### Per-category
+
+| Category | Cases | top-3 |
+|---|---|---|
+| landmark | 17 | 17/17 (100.0%) |
+| abbreviation | 15 | 15/15 (100.0%) |
+| glued | 7 | 7/7 (100.0%) |
+| typo | 14 | 14/14 (100.0%) |
+| alias | 15 | 15/15 (100.0%) |
+| negative | 7 | refused 7/7 (100.0%) |
+
+The gate closes mechanically: `npm run search:corpus` exits 0 only when top-3 >= the
+corpus's pinned `top3_hit_rate` (0.9) AND every negative is refused; the same measurements
+are asserted in-process by `search/test/corpus.test.mjs` (CO1–CO8) inside
+`npm run search:test`, so a regression fails the suite, not just the standalone runner.
+
+### Escalation lever pulled (D-14)
+
+1. **None — the threshold was met on the first run.** No alias/normalizer table edits were
+   needed: no rows were added to `search/src/rules/abbreviations.ts`, no aliases were added
+   to the gazetteer, and the corpus was not edited. The numbers above ARE the first-run
+   measurement. (The ladder — lever 1 table edits → lever 2 WASM geocoder → lever 3
+   Photon-on-VPS — is printed by the runner whenever a future run fails; it was never
+   climbed this phase.)
+
+The two top-1 misses (both still top-3 hits) are expected scorer behaviour, not gaps:
+"KCLC" lands in a three-way 0.45 fuzzy tie resolved id-ascending (suria-klcc third), and
+"Sunway Vellocity" legitimately rides the PREFIX tier via the "Sunway" alias, which outranks
+the fuzzy hit on the full name — the disjoint-tier design doing what it is specified to do.
+
+### Corpus corrections
+
+None — every case passed as pinned; no `expectId` was edited and `threshold.top3_hit_rate`
+is still `0.9`.
+
+### Coordinate verification
+
+Method: one-shot maintainer-time check (not a test, never a runtime path). For 10 sampled
+seed entries, `GET https://nominatim.openstreetmap.org/search?format=jsonv2&q=<name>, Kuala
+Lumpur&limit=1` with the identifying User-Agent `araharah-coordinate-verify/1.0
+(+https://github.com/araharah)` (a missing UA is the 406 trap — the same discipline as the
+Overpass script), comparing max(|Δlat|, |Δlng|) against a 0.01° tolerance.
+
+**Outcome: 8 of 10 sampled within 0.01°** (deltas 0.0001°–0.0047°).
+
+- `pavilion-kl` — OUT by 0.018°: the committed coordinate was wrong (lng 101.695, ~2 km
+  west of the mall). Nominatim places Pavilion Kuala Lumpur at (3.1492, 101.7130); the
+  entry was corrected to (3.149, 101.7132) — post-fix delta 0.0002°. This is a dataset
+  correction, not a corpus edit; the search corpus is coordinate-blind and all suites stayed
+  green.
+- `bukit-bintang` — OUT by 0.017°: an area-vs-point discrepancy. "Bukit Bintang" is a
+  district; Nominatim's first hit is a district centroid, while the committed point is the
+  Jalan Bukit Bintang shopping strip itself. No change — the committed point is the
+  navigation-relevant landmark.
+
+This verified 10 of 30 seed entries; a full 30-entry pass is worth doing after the next
+top-up lands (see Known limitations). Fallback invariant if Nominatim is unreachable at a
+future re-check: the committed-bbox gate (G5, `search/test/gazetteer.test.mjs`) still
+guarantees every entry sits inside the KL metro box.
+
+### Reproduce
+
+```sh
+npm run search:corpus   # the D-14 gate: exit 0 only on threshold + zero leaks
+npm run search:test     # CO1–CO8 assert the same measurements in-process
+```
+
+### Known limitations
+
+- The corpus is hand-written and small; it measures the documented local shorthand, not every
+  phrasing a KL driver might use.
+- Out-of-KL queries are refused, not routed — there is no backend #2 or #3 in v1.
+- The fuzzy tier performs a full-candidate OSA scan when a query has no cheap-tier hit (the
+  pure-typo path) — measured at ~8.2 ms/query against ~2 000 alias pairs at D-07's 500-entry
+  scale (RESEARCH §Verification A1), and at 1.07 ms/query against this 30-entry seed corpus,
+  inside the 10 ms Workers Free CPU limit. This is a RECORDED scaling decision, not an
+  oversight (RESEARCH directive #1): if a future top-up pushes the dataset toward D-07's
+  500-entry ceiling and CPU approaches the limit, the documented next step is a cheap
+  blocking key (first-letter + length band) in front of the OSA tier — measured against this
+  corpus before it ships.
+- The two top-1 misses show the id-ascending tie-break can put a same-tier neighbour first
+  on short fuzzy ties; top-3 (the D-14 gate) is unaffected. If top-1 quality ever matters
+  beyond this, the lever is a deterministic secondary signal (e.g. category boost), not a
+  threshold change.