chore: adopt noImplicitOverride and noFallthroughCasesInSwitch repo-wide

[lmorchard]

Takes two of the three strict flags WXT 0.21 introduced, so that #688 becomes a single question about noUncheckedIndexedAccess instead of three tangled ones. Refs #688 (does not close it).

Why these two and not the third

I measured each flag separately, deduplicated across packages (cli/server/extension all typecheck core via paths, so raw per-package counts double-count):

Flag	Unique sites
noFallthroughCasesInSwitch	0
noImplicitOverride	5 — 3 files, all core/src
noUncheckedIndexedAccess	55 as CI is configured today, +145 more in core/test

This PR is the two free ones. The noUncheckedIndexedAccess breakdown is 21 extension/test, 14 core/src, 10 cli/test, 9 extension/src, 1 extension/e2e — 31 of 55 in tests, where the flag buys close to nothing.

The five override annotations are real

Not appeasement — each is a genuine override of a base-class member:

• core/src/events.ts:547 — emit over EventEmitter.emit. This one already had an "Override emit to also trigger wildcard listeners" doc comment while lacking the keyword.
• core/src/loggers/filter.ts — initialize, dispose over LoggerWrapper
• core/src/loggers/metricsCollector.ts — initialize, dispose over LoggerWrapper

Verification

I checked the flags actually bite rather than sitting inert in config:

# with one 'override' keyword removed:
src/loggers/filter.ts(39,3): error TS4114: This member must have an 'override' modifier...
# with a deliberate switch fallthrough added:
src/m688probe.ts(3,5): error TS7029: Fallthrough case in switch.

Both probes reverted; tree clean. Also green: full pnpm run check (typecheck across all packages, schema drift gate, 1600 tests) and pnpm run build + CLI startup on node 24.

Note on placement

Enabled in each package's tsconfig because there's no shared base config — core/cli/server are standalone and the extension extends WXT's generated one. Introducing a shared base is a bigger refactor than this warrants, but it does mean four files to touch for the next flag.

What's left on #688

Only noUncheckedIndexedAccess. My read, from having now read all 24 production sites across two audit passes: zero are real bugs, so the case for it is forward-looking (catching future unguarded indexing) rather than remedial. Worth deciding on those terms. Also surfaced while measuring: core/tsconfig.json excludes **/*.test.ts, so core's 993 tests are never typechecked by anything — clean at baseline today, but that's where 145 of the 200 sites live.

[Copilot]

🟢 Approval recommended

No unresolved blocking issues were identified.

Pull request overview

Enables noImplicitOverride and noFallthroughCasesInSwitch across the repository.

Changes:

• Updates TypeScript configurations across packages.
• Removes obsolete extension opt-outs.
• Adds five required override annotations in core.

File summaries

File	Summary
packages/server/tsconfig.json	Enables strict compiler flags.
packages/extension/tsconfig.json	Aligns extension configuration with the adopted flags.
packages/core/tsconfig.json	Enables strict compiler flags.
packages/core/src/loggers/metricsCollector.ts	Marks logger lifecycle methods as overrides.
packages/core/src/loggers/filter.ts	Marks logger lifecycle methods as overrides.
packages/core/src/events.ts	Marks emit as an override.
packages/cli/tsconfig.json	Enables strict compiler flags.

Review details

• Files reviewed: 7/7 changed files
• Comments generated: 0
• Review effort level: Lite

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