fix(ts-watch): invalidate deleted sources in the CLI program

Follow-up to #922. The polling watcher now reports one removal and a later re-addition, but the actual home-tsc --watch loop in packages/ts_cli/src/tsc_main.zig explicitly skips every .removed change before Program.updateSource/recompileChanged. Program currently exposes updateSource but no corresponding source-removal operation. This means deleting an imported or root file can leave stale source, diagnostics and emit state until another event; #922 does not solve this CLI-level gap.

Acceptance: model source removal in Program and reverse dependency invalidation without substituting empty source or suppressing diagnostics; make the watch loop process removal and publish the complete current diagnostic/output set; cover delete, repeated absence, same-metadata recreate, imported-file deletion/recreation, and error/OOM paths with actual CLI or Program controls. Preserve existing file identities and unchanged-source incremental behavior. No filename-specific workaround or passing credit from watcher-only tests.

Prerequisite #924 is fixed by 40cfdba: the watch loop now observes initially loaded transitive sources, not only root inputs, with a guarded real-Program regression. This does not close #923: the current watch loop still skips .removed events, and Program has no source-removal API. A correct removal must preserve stable FileIds, invalidate the old importer closure before clearing edges, drop source/owner storage, exclude absent files from all compile/reference/output paths, and handle canonical package-dedup redirects without treating missing files as empty modules. Recreated paths and imports added after the initial closure also need explicit coverage. No deletion pass is claimed.

Guarded live deletion control on current main 5d54d1a (Darwin arm64), using a temporary two-file project that was removed afterward:

• Both Home home-tsc and local TypeScript 5.7.3 started with 0 errors for main.ts importing dep.ts (number export).
• After deleting dep.ts, Home printed no incremental-compilation event over the next 10 seconds. It did notice a later re-addition containing a string export and reported importer TS2322, so the loop remained alive.
• In the separate TypeScript reference run, deletion immediately produced an incremental event with TS2307 at main.ts(1,23); repeated absence produced no second event, and recreating the original number export produced another event and 0 errors.
• Each persistent watch was run alone under the unchanged 3,840 MB run_bounded guard and intentionally ended at its 35-second wall-clock deadline (exit 124); that is not a suite pass.

Code trace: tsc_main.zig still skips .removed before Program.updateSource/recompileChanged. Program File.source is a borrowed nonoptional slice from Program.sources, and compilation/owner/importer invalidation assumes physical presence; Resolver also memoizes resolution and file-existence results. A correct implementation must represent absence explicitly, invalidate the old reverse closure before clearing edges, clear filesystem-resolution caches, keep stable FileIds for recreation, exclude absent files from compilation/emit, and produce importer TS2307 rather than treating missing bytes as an empty module. No production source or test assertion was changed in this control.

Watch-mode prerequisite landed on origin/main in bbe07c5 (3 files, Glenn author/committer, no coauthors): resolver filesystem caches and their arena are invalidated between successful watch revisions after the checker adapter is disposed. A guarded real home-tsc --watch control moved from missing-import TS2307 to imported-value TS2322 after dep.ts was created and the importer changed. The persistent watch was intentionally stopped at 35 seconds (exit 124), not counted as a suite pass. This does not implement Program source removal, absent FileId state, package-redirect reconciliation, or deletion/recreation diagnostics; #923 remains open. See #925 for exact tests and a separate positive-cache limitation.

Pushed 8510bbc directly to origin/main (four files; Glenn author and committer). Program now retires a removed source while preserving its FileId, invalidates the old reverse importer closure before clearing edges, excludes absent files from compilation/reference/emission, and reconciles package-identity redirects. The CLI watch loop processes removed events and reports TS6053 for absent explicit roots instead of silently retaining old source.

Verification under the 3,840 MB guard: watch-program 7/7 (including removal, TS2307, repeated absence, same-mtime-and-size recreation, stable FileId), tsc_main 52/52, ts_cli 81/81; ts_program, ts_resolver, and ts_driver reported cached success for current sources. Earlier guarded live home-tsc controls on these source changes showed imported-file deletion -> TS2307 -> clean recreation, and explicit-root deletion -> TS6053 -> clean recreation; the intentionally bounded persistent watchers exited 124, not as passing suites. Program tests also cover root recreation, package redirect promotion, and allocation-failure atomicity.

Leaving the issue open pending broader output-file lifecycle and mixed-batch failure verification; this is not a claim that all watch-mode acceptance or the full TypeScript suite is green.

Follow-up output-lifecycle control for 8510bbc: ran one reference TypeScript 5.7.3 watch and one freshly rebuilt Home home-tsc watch, sequentially under the 3,840 MB guard, on the same temporary two-file project with JS emission enabled. Both initially emitted main.js and dep.js with 0 errors. Deleting dep.ts produced importer TS2307 in both; both retained the previously emitted dep.js on disk and re-emitted main.js. Thus removing stale dep.js would diverge from the reference behavior. Each persistent watch intentionally hit its 45-second wall bound (exit 124), which is not a suite pass. The fixture was removed afterward.

Together with the guarded Program allocation-failure test and watch retry-after-update/compile-OOM test in the pushed commit, this covers the deletion/recreation and publication behavior requested here. The broader TypeScript and Bun suite goals remain separately open.