The file editor page's Server-Timing names its phases: session, each read, render #3535

GET /:owner/:name/edit/:ref/*path now answers with Server-Timing phases session, repo, blob, refs and render, after the usual app. I couldn't run the type check here: bun install and bun x tsc --noEmit both fail with a read-only tempdir error. The new test and the existing editor suite (test/web-editor.test.ts) pass.

The phases use notePhase/timePhase/timePhaseAsync from src/core/route_timing.ts, as milestones.ts does:

• session is the session time the server already measured.
• repo covers repo lookup, sign-in and permission checks.
• blob is the file read.
• refs covers blankDraft, which reads the branch list and checks admin rights. It wraps the call in editPage rather than going inside mustBranchFrom, so newFilePage and the other callers of blankDraft are unchanged.
• render wraps editorPage, which includes the highlight-asset read.

Order, errors, body, status codes and caching are unchanged, and nothing new is computed for the header. The change is in src/web/pages/edit.ts.

test/edit-timing.test.ts requests the editor as a signed-in owner and asserts each phase name appears with a dur= value. It fails without the change and checks names only, never a time.

On a request that exits early, such as a 404 or a redirect to sign in, the header lists only the phases that ran.

Closes #3499

The file editor page (GET /:owner/:name/edit/:ref/*path) now answers with Server-Timing phases session, repo, blob, refs and render, after app. I haven't been able to run tsc here (the sandbox's tempdir is read-only), so the type check is still unconfirmed on my side. The forge's check will be the first real run of it on this push.

• Check failure: it was a type error. Inside the timed closure TypeScript no longer knew the blob was text, so blob.value.body failed. The file is now decoded before the closure in src/web/pages/edit.ts, which keeps the narrowing.
• Phases: each one uses notePhase/timePhase/timePhaseAsync from src/core/route_timing.ts, as milestones.ts does. The wrapped reads keep their order and errors, and nothing new is computed for the header. Body, status codes and caching are unchanged.
• Test: test/edit-timing.test.ts signs in, requests the editor and asserts each phase name appears with a duration. Without the change it fails. It asserts names only, never a wall-clock time.
• Test run: that test and test/web-editor.test.ts pass (31 tests).
• refs phase: it wraps blankDraft, which also checks admin rights. I wrapped the call in editPage instead of timing inside mustBranchFrom, so newFilePage and other callers of blankDraft don't gain a phase.
• Early exits: a request that exits early (404, sign-in redirect) lists only the phases that ran.