feat(obj-2): multi-feature mapping backfill (name+dev+district), threshold 0.75

Issue #307 OBJ-2. Adds GIST trgm index on objective_lots.project_name so the
LATERAL similarity() probe runs via bitmap index scan instead of seq-scan-per-row
(database-expert worker identified this perf bottleneck via EXPLAIN).

Composite score = name_sim*0.6 + dev_match*0.25 + district_match*0.15.
Threshold composite >= 0.75 for auto-accept.

ON CONFLICT (objective_complex_name, objective_group) DO NOTHING — idempotent.
REFRESH mv_layout_velocity CONCURRENTLY after backfill (outside tx) so Site
Finder sees new mappings immediately.

Expected mapping count: 142 -> 200+ (realistic ceiling given Objective
project_names vs DOM.РФ comm_names naming gap).

data/sql/116_obj2_multi_feature_matcher.sql

@@ -0,0 +1,96 @@
+-- 116_obj2_multi_feature_matcher.sql
+-- Issue #307 OBJ-2: backfill objective_complex_mapping via multi-feature scoring
+-- (name_sim 60% + dev_match 25% + district_match 15%).
+--
+-- Adds trgm gist index on objective_lots.project_name FIRST so the LATERAL
+-- similarity() probe runs as bitmap index scan instead of seq-scan-per-row.
+--
+-- Inserts auto-accepted matches at composite >= 0.75 with match_method='multi_feature_v1'.
+-- ON CONFLICT (objective_complex_name, objective_group) DO NOTHING — idempotent.
+-- REFRESH mv_layout_velocity CONCURRENTLY at the end so Site Finder sees new mappings.
+--
+-- Verification (run after COMMIT, outside migration):
+--   SELECT COUNT(*) FROM objective_complex_mapping;                       -- expect 200+
+--   SELECT * FROM objective_complex_mapping WHERE domrf_obj_id=64701;     -- Малевич still mapped
+--   SELECT match_method, COUNT(*) FROM objective_complex_mapping GROUP BY 1;
+
+-- The pg_trgm extension is already installed (used by existing migrations 99/103/104).
+
+-- ── Step 1: GIST index for trgm similarity probes ───────────────────────────
+-- IF NOT EXISTS keeps migration idempotent.
+CREATE INDEX IF NOT EXISTS objective_lots_project_name_trgm_idx
+    ON objective_lots USING gist (project_name gist_trgm_ops);
+
+-- ── Step 2: composite-score backfill ────────────────────────────────────────
+BEGIN;
+
+WITH unmapped_domrf AS (
+    SELECT o.obj_id, o.comm_name, o.dev_name, o.district_name
+      FROM domrf_kn_objects o
+     WHERE o.is_ekb = true
+       AND o.comm_name IS NOT NULL
+       AND NOT EXISTS (
+           SELECT 1 FROM objective_complex_mapping m WHERE m.domrf_obj_id = o.obj_id
+       )
+),
+unmapped_obj AS (
+    SELECT DISTINCT project_name, developer, district
+      FROM objective_lots
+     WHERE project_name IS NOT NULL
+       AND project_name NOT IN (
+           SELECT objective_complex_name FROM objective_complex_mapping
+       )
+),
+pair_scores AS (
+    SELECT
+        d.obj_id,
+        o.project_name,
+        similarity(d.comm_name, o.project_name)                              AS name_sim,
+        (regexp_replace(lower(coalesce(d.dev_name, '')),  '[^а-яa-z0-9]', '', 'g')
+         = regexp_replace(lower(coalesce(o.developer, '')), '[^а-яa-z0-9]', '', 'g')
+        )::int                                                                AS dev_match,
+        (
+            coalesce(d.district_name, '') ILIKE '%' || coalesce(o.district, '') || '%'
+         OR coalesce(o.district, '')      ILIKE '%' || coalesce(d.district_name, '') || '%'
+        )::int                                                                AS district_match
+      FROM unmapped_domrf d
+      CROSS JOIN LATERAL (
+          SELECT u.project_name, u.developer, u.district
+            FROM unmapped_obj u
+           WHERE similarity(d.comm_name, u.project_name) > 0.3
+           ORDER BY similarity(d.comm_name, u.project_name) DESC
+           LIMIT 3
+      ) o
+),
+ranked AS (
+    SELECT
+        obj_id, project_name, name_sim, dev_match, district_match,
+        (name_sim * 0.6 + dev_match * 0.25 + district_match * 0.15)         AS composite,
+        ROW_NUMBER() OVER (
+            PARTITION BY obj_id
+            ORDER BY (name_sim * 0.6 + dev_match * 0.25 + district_match * 0.15) DESC,
+                     name_sim DESC
+        )                                                                    AS rn
+      FROM pair_scores
+)
+INSERT INTO objective_complex_mapping
+    (objective_complex_name, domrf_obj_id, objective_group,
+     match_method, match_score, is_reviewed, note)
+SELECT
+    r.project_name,
+    r.obj_id,
+    'Екатеринбург',
+    'multi_feature_v1',
+    r.composite,
+    false,
+    'OBJ-2 multi-feature 2026-05-17 (name 0.6 + dev 0.25 + district 0.15)'
+  FROM ranked r
+ WHERE r.rn = 1
+   AND r.composite >= 0.75
+ON CONFLICT (objective_complex_name, objective_group) DO NOTHING;
+
+COMMIT;
+
+-- ── Step 3: REFRESH MV so Site Finder uses new mappings ─────────────────────
+-- CONCURRENTLY requires the MV to not be in a tx; run outside BEGIN/COMMIT.
+REFRESH MATERIALIZED VIEW CONCURRENTLY mv_layout_velocity;