refactor(plex): the browse, detail, people and collection pages read through queries and write through the service

The HTTP files browse, detail, people, collections and _shared do no database work of their own
now. New plex/queries.py (the rows a page shows, a user's watch state through userscope),
plex/service.py (the info pages' enrichment, a collection's editable flag, the row kept after a
failed follow-up read, the person bio's background fetch; none commits), plex/library.py (the
unified browse feed, its search and facets) and plex/collections.py (a collection's source,
editability, card, certificate and member order). Every watch-state join in the moved code names
its owner through owned_by.

Pins 354 -> 178 in 4 files; basedpyright baseline 132 -> 118.

docs/gates.md

@@ -113,7 +113,7 @@ project checks needs a row.
 | CVE gate | HIGH/CRITICAL with a fix available only | `--ignore-unfixed` + `--severity HIGH,CRITICAL`: a finding with no fix cannot be acted on by an upgrade; it shows in the scan output. A fixable one fails the publish, and the only way past it is `.trivyignore.yaml`. | 0 open (E32 S1) |
 | npm audit | `--omit=dev --audit-level=high` | What ships to the browser, at high or above. The dev toolchain's advisories were burned down by hand in E32 S1 (18 → 0). | 0 |
 | knip | `entry` — one file added | Not a narrowing: knip's Vite plugin reads entries from index.html only, so the shared link's page (`watch.html` → `src/watchMain.tsx`) is named here, or the lane reports that whole entry unused. It adds files to the lane, never takes any out. | 1 entry |
-| unit fence | the database work the HTTP layer still does, pinned | `backend/tests/test_unit_fences.py`: a unit's route file may not build SQL, call the session's data methods, set a model's attributes or import a unit's tables; a core route may not import a unit's tables. Switched on unit by unit: `ALLOWED` pins each file's count exactly, so a rise fails and a fall fails until the pin is lowered — the list may only shrink. End state: empty, and the pin mechanism goes. A unit in `FENCED` is held below its HTTP layer too: its code reads another unit's tables only along `READS`, writes them never, filters owners through `userscope`, and commits only where `UNIT_COMMITS` names a job's own session. | 826 in 23 files (E42 S0) → 667 in 19 (S1: Capture 0, fenced) → 525 in 14 (S2: Reader 0, fenced) → 354 in 9 (S3: Catalog 0, fenced; core routes 0) |
+| unit fence | the database work the HTTP layer still does, pinned | `backend/tests/test_unit_fences.py`: a unit's route file may not build SQL, call the session's data methods, set a model's attributes or import a unit's tables; a core route may not import a unit's tables. Switched on unit by unit: `ALLOWED` pins each file's count exactly, so a rise fails and a fall fails until the pin is lowered — the list may only shrink. End state: empty, and the pin mechanism goes. A unit in `FENCED` is held below its HTTP layer too: its code reads another unit's tables only along `READS`, writes them never, filters owners through `userscope`, and commits only where `UNIT_COMMITS` names a job's own session. | 826 in 23 files (E42 S0) → 667 in 19 (S1: Capture 0, fenced) → 525 in 14 (S2: Reader 0, fenced) → 354 in 9 (S3: Catalog 0, fenced; core routes 0) → 178 in 4 (S4a: Plex browse, detail, people, collections 0) |
 | React Compiler | the functions it skips, pinned | `components/compilerCoverage.contract.test.ts` — the list may only shrink. End state: only VirtualGrid (TanStack Virtual, an IncompatibleLibrary) remains. | 93 (E32 S1) → 29 (E32 S3) → 1, VirtualGrid (E32 S4) |
 
 ## Accepted findings