Absorb: Settings > Features and /api/v1/features read git for every app on every request #9650

The features list now reads git only for apps whose default-branch tip has moved, and the nav menu fetches each app record once. The gate, tsc, the design lint, and test/features.test.ts plus test/mcp-size.test.ts all pass. I did not measure the speedup against a real forge with hundreds of apps.

• Cache: declaredFeature in src/actions/features.ts keeps the parsed forge.json declaration keyed by the tip's commit id. A repeat load of /settings/features, GET /api/v1/features or the features MCP list costs one tip lookup per app instead of a read and parse. The cache holds up to 2000 entries and is cleared whole when full, so the next load after that re-reads each app once.
• Nav: absorbedForNav now returns the app record it already fetched. featureItems in src/web/layout.ts uses it and no longer calls getAppById.
• Tests: two new tests in test/features.test.ts.

- One checks that the same tip returns the identical cached result and that a new commit reads again. - One adds 20 more absorbed apps and checks the record rides along in the nav. It also asserts a 25 ms average for absorbedForNav and 500 ms for a full /settings page.

• Left out: I did not add a per-phase route-timing assertion, so the budget is wall-clock. The /apps/open wake-up of a sleeping app is unchanged. The per-app canRead and repo lookups in absorbedForNav are still linear.

Closes #9543

The features list now reads git only for apps whose default-branch tip has moved, and the nav menu fetches each app record once. The gate, tsc, the design lint, and test/features.test.ts plus test/mcp-size.test.ts all pass. I did not measure the speedup against a real forge with hundreds of apps.

• Cache: declaredFeature in src/actions/features.ts keeps the parsed forge.json declaration keyed by the tip's commit id. A repeat load of /settings/features, GET /api/v1/features or the features MCP list costs one tip lookup per app instead of a read and parse. The cache holds up to 2000 entries and is cleared whole when full, so the next load after that re-reads each app once.
• Nav: absorbedForNav now returns the app record it already fetched. featureItems in src/web/layout.ts uses it and no longer calls getAppById.
• Tests: two new tests in test/features.test.ts.

- One checks that the same tip returns the identical cached result and that a new commit reads again. - One adds 20 more absorbed apps and checks the record rides along in the nav. It also asserts a 25 ms average for absorbedForNav and 500 ms for a full /settings page.

• Left out: I did not add a per-phase route-timing assertion, so the budget is wall-clock. The /apps/open wake-up of a sleeping app is unchanged. The per-app canRead and repo lookups in absorbedForNav are still linear.

The check failed because no commit message had a "Try:" line. I added an empty commit that has one and pushed it. bun scripts/gate.ts printed nothing after it, which I'm reading as a pass. I did not re-run tsc or the tests, since the new commit changes no code.

The line reads: "Try: open /settings/features on the preview twice, or GET /api/v1/features; the second load reads no git for unmoved apps."

The code is as in my earlier message. The features list reads git only for apps whose default-branch tip has moved. The nav menu fetches each app record once.

I replaced the two wall-clock assertions in test/features.test.ts with a count of SQL statements, and pushed. test/features.test.ts passes (16 tests), tsc is clean, and the gate printed nothing. I have not seen the forge's full check run on this push.

The 20-app test now counts the statements absorbedForNav runs and bounds them at 2 + 3 * n. With 21 absorbed apps it ran 64 statements, about three per app plus one for the list, so the bound has little slack. A return to the old per-app re-fetch or any other extra read per app would exceed it. I also dropped the 500 ms page-render timing. The test still renders /settings and checks that it contains "Many 19", but no longer times it.

The code change is the same as before: the features list reads git only for apps whose tip moved, and the nav menu fetches each app record once. The new commit has a Try: line for the gate rule.