C7 · /authors proximity search (PR7)

C7/PR7 city-centric proximity search on /authors — BUILT + verified in worktree feature/authors-optimization (isolated DB lounge_feature_authors_optimization). Commit **7a540a4c** ("Add city-centric proximity search to /authors (C7/PR7)", Brief: #253 trailer). **Files (3, +654/-8):** - `app/Livewire/RedditUserIndex.php` — radius prop (0/10/25/50/100, queryString except 0, snap-to-0 validation), `near` sort added to valid_sort, proximity flags in render(), three new private methods: `resolveNearbyLocationIds()` (box + ST_Distance_Sphere + is_search_visible gate, 6h cache), `resolveNearbyAuthorIds()` (GROUP BY dedup, karma/active/joined/near sort, followed compose, 15m cache), `paginateCachedIds()` (LengthAwarePaginator via Paginator::resolveCurrentPage). updating()/locationSelected()/clearLocation()/resetFilters() reset radius + both cursor & page. - `resources/views/livewire/reddit-user-index.blade.php` — raw-Tailwind radius segmented control (shown when a location chip active), coarse-center disabled state + inline hint, Nearest sort option (only under active radius). - `tests/Feature/Livewire/RedditUserIndexTest.php` — 8 new proximity tests + seedGeoLocation/addPivotRow helpers. **Query/index approach:** bounding-box on `locations_lat_lng_index` (lat band lead) → `ST_Distance_Sphere(POINT(lng,lat),…)` HAVING-refine to true circle → gate `merged_into_id IS NULL AND city_id IS NOT NULL AND is_search_visible=1` → LIMIT 64 nearest (cached 6h). Candidate = pivot-first `location_id IN(…64…) AND is_visible=1` on `lru_loc_vis_karma`, `GROUP BY reddit_user_id` (exact dedup — C5 denorm columns identical across a user's rows), cap 1500, cached 15m keyed by (location_ids|sort|dir|only_verified|recently_active|followed_only|per-user scope). Offset-paginated in memory (LengthAwarePaginator; cursor can't keyset a GROUP-BY-over-IN — doc 20 §4.4). **Brief deltas honored:** (1) quality gate = #242 `is_search_visible`, NOT a new `visible_author_count` column → **no migration added**; (2) sort offers BOTH karma (default) + distance `near` per decision #63 — near ranks by each author's nearest location via `MIN(FIELD(location_id, …nearest-first…))`, karma-desc tiebreak; (3) followed_only composes (README §0.4) folded into cache sig; (4) coarse (non-city) center = VISIBLE disabled control + inline hint (README §0.2), degrades to exact, no toast. Admin-toggle / only_indexed-off → uncached `whereExists(location_id IN nearby-set)` + cursorPaginate (doc 20 §6). Precedence q > proximity > exact. **Verification:** `php artisan test --filter=RedditUserIndexTest` → **17/17 green** (9 existing + 8 new: nearby/far bounds, 25-mi radius bounding, GROUP BY dedup via substr_count equality, coarse-center degrade+hint, out-of-set→0, distance-vs-karma sort both directions, is_search_visible gate, followed∩proximity). Pint clean; PHPStan level 5 clean on the component (full run blocked by a pre-existing phpstan-baseline entry referencing a deleted file — not mine; ran via scratch config w/ reportUnmatchedIgnoredErrors:false). Box-query EXPLAIN on the clone: index-driven, `locations_lat_lng_index` in possible_keys, no full scan (locally the optimizer picks is_search_visible index since the clone has 0 qualified geo-locations — #242 sweep not run here; prod's ~18K qualified geo rows make the lat-band the driver as doc 20 §3.2 predicts; prod timing validation deferred to epic §8). Full-page smoke tests 500 across the board (about/subscribe/home included) due to a missing Vite manifest (no node_modules/mix in this worktree) — pre-existing env gap, unrelated; my blade is exercised by the passing Livewire tests. Blocks #256 (C10/PR10 frontend/UX pass) which layers the visual polish.

Child of /authors optimization epic (#239). **Depends on C2 (geo index) + C6 (pivot-first) + #242 (qualified location set).** Build in `feature/authors-optimization` worktree. Implement **PR7** (doc 20): city-centric radius search on `/authors` — bounding box → `ST_Distance_Sphere` refine → cap to the 64 nearest → pivot-first `IN` query deduped by `GROUP BY reddit_user_id` → cached + offset-paginated. `radius` prop + query-string + reset wiring; nearby-set (6h) + candidate (15m) caches; `LengthAwarePaginator`. **Deltas from the design (operator decisions):** - Radius set `{0,10,25,50,100}` mi (per README §0). - **Sort offers BOTH karma + distance, default karma** (#63) — not karma-only. - Candidate set is #242's **qualified** locations (the doc-30 `visible_author_count` quality gate is replaced by #242's `is_search_visible` flag). Validation: cold Dallas-area build in target range, warm hits <1ms; `GROUP BY` dedups a user in multiple nearby locations; state-level centers (`city_id IS NULL`) force radius 0.