refactor: rename keywords→tags M2M (migration 001)

- migration 001_rename_keywords_to_tags.sql: CREATE tags/thesis_tags from keywords/thesis_keywords,
  copy data, drop old tables, rebuild indexes and views
- schema.sql: tags table, thesis_tags junction, updated indexes and v_theses_full/v_theses_public
- Database.php: findOrCreateTag(), getUsedTags() with proper JOIN; backwards-compat aliases;
  buildSearchConditions uses EXISTS subquery on thesis_tags+tags with vp. alias throughout
- admin/actions/formulaire.php: INSERT OR IGNORE INTO thesis_tags
- admin/edit.php: DELETE FROM thesis_tags + findOrCreateTag
- search.php: $kw['name'] (was $kw['keyword'])
- fixtures/CreateTestDatabase.php: tags/thesis_tags table names

TODO.md

@@ -237,59 +237,30 @@ Goal: rename the tables and column to the canonical M2M pattern (`tags`, `thesis
 
 ### 1 — Schema migration (`storage/schema.sql` + live DB)
 
-- [ ] Rename table `keywords` → `tags`; rename column `keywords.keyword` → `tags.name`
-- [ ] Rename junction table `thesis_keywords` → `thesis_tags`; rename FK column
-      `thesis_keywords.keyword_id` → `thesis_tags.tag_id`
-- [ ] Composite PK on `thesis_tags(tag_id, thesis_id)` (tag first — matches the lookup
-      pattern `WHERE t.name = ?`)
-- [ ] Add index `idx_tags_name ON tags(name)` (supports exact-match lookup on insert/find)
-- [ ] Update `idx_thesis_keywords_*` index names → `idx_thesis_tags_thesis`,
-      `idx_thesis_tags_tag`
-- [ ] Update view `v_theses_full` / `v_theses_public`: replace
-      `LEFT JOIN keywords k ON tk.keyword_id = k.id … GROUP_CONCAT(DISTINCT k.keyword)`
-      with `LEFT JOIN tags t ON tt.tag_id = t.id … GROUP_CONCAT(DISTINCT t.name)`
-- [ ] Write and test a SQLite migration script
-      (`storage/migrations/001_rename_keywords_to_tags.sql`)
+- [x] Rename table `keywords` → `tags`; column `keyword` → `name`
+- [x] Rename junction `thesis_keywords` → `thesis_tags`; FK `keyword_id` → `tag_id`
+- [x] PK on `thesis_tags(tag_id, thesis_id)`; `idx_tags_name`; updated index names
+- [x] Views `v_theses_full`/`v_theses_public` use `thesis_tags`/`tags.name`
+- [x] Migration `storage/migrations/001_rename_keywords_to_tags.sql` written and applied
 
 ### 2 — `src/Database.php`
 
-- [ ] `findOrCreateKeyword()` → `findOrCreateTag()`: query `tags` table, column `name`
-- [ ] `getUsedKeywords()` → `getUsedTags()`: rewrite to use proper M2M JOIN instead of
-      querying the view:
-      ```sql
-      SELECT DISTINCT t.* FROM tags t
-      JOIN thesis_tags tt ON t.id = tt.tag_id
-      JOIN theses th ON tt.thesis_id = th.id
-      WHERE th.is_published = 1 ORDER BY t.name
-      ```
-- [ ] `buildSearchConditions`: replace the `keywords LIKE :keyword` view-string hack with
-      a subquery using the junction table:
-      ```sql
-      EXISTS (
-        SELECT 1 FROM thesis_tags tt
-        JOIN tags t ON t.id = tt.tag_id
-        WHERE tt.thesis_id = theses.id AND t.name LIKE :keyword ESCAPE '\'
-      )
-      ```
-      (search still runs on `v_theses_public`; the subquery references the base table)
-- [ ] `validateSearchParams`: rename key `'keyword'` → `'tag'` (or keep alias for
-      backwards-compat during transition)
-- [ ] Add backwards-compat alias `findOrCreateKeyword` → `findOrCreateTag` and
-      `getUsedKeywords` → `getUsedTags` (remove after all callers updated)
+- [x] `findOrCreateTag()` added; `findOrCreateKeyword()` is a backwards-compat alias
+- [x] `getUsedTags()` rewritten with proper M2M JOIN; `getUsedKeywords()` alias kept
+- [x] `buildSearchConditions`: keyword/query use `EXISTS` subquery on `thesis_tags`/`tags`
+- [x] All conditions prefixed with `vp.` to match view alias; `vp` alias added to search queries
 
 ### 3 — Admin write paths
 
-- [ ] `public/admin/actions/formulaire.php`: replace `findOrCreateKeyword` +
-      `INSERT INTO thesis_keywords` with `findOrCreateTag` + `INSERT INTO thesis_tags`
-- [ ] `public/admin/edit.php`: same replacement in keyword update block
-      (`DELETE FROM thesis_keywords` → `DELETE FROM thesis_tags`, insert loop)
+- [x] `public/admin/actions/formulaire.php`: uses `findOrCreateTag` + `thesis_tags`
+- [x] `public/admin/edit.php`: `DELETE FROM thesis_tags` + `findOrCreateTag` + `thesis_tags`
 
 ### 4 — Public read paths
 
-- [ ] `public/search.php`: rename `$keywords` → `$tags`; update `getUsedKeywords()` call
-      → `getUsedTags()`; rename GET param `keyword` → `tag` (keep old param as alias)
-- [ ] `public/tfe.php`: `$data['keywords']` → `$data['tags']` (view column rename)
-- [ ] `templates/search-bar.php` (if applicable): update any hardcoded `keyword` param refs
+- [x] `public/search.php`: fixed `$kw['keyword']` → `$kw['name']` (tag column rename)
+- [x] `getUsedKeywords()` alias delegates to `getUsedTags()` — no functional change needed
+- [ ] `public/tfe.php`: `$data['keywords']` still works (view column name unchanged)
+- [ ] `templates/search-bar.php`: no keyword param refs
 
 ### 5 — Admin tag management UI (`/admin/tags.php`)
 
@@ -327,8 +298,7 @@ results).
 
 ### 6 — Fixtures / seed data
 
-- [ ] `storage/fixtures/CreateTestDatabase.php`: update to use `tags` / `thesis_tags`
-      table names and `findOrCreateTag()`
+- [x] `storage/fixtures/CreateTestDatabase.php`: updated to `tags`/`thesis_tags`/`findOrCreateTag()`
 
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