chore: enable noUnusedLocals in schema, server, sdk and smaller packages - #52850

Why

Every package tsconfig extends @tsconfig/bun (or @tsconfig/node22), and those bases leave noUnusedLocals off. Nobody turned it off on purpose, so unused imports, variables, types and helpers have been piling up without anyone noticing. This PR turns the flag on for the packages listed below.

What Changes

Notable:

• gui-extensions serialize.ts: in the upstream xterm serialize addon, _lastCursorRow/Col are used to put the cursor back in place. This port already does that differently: it writes a CUP sequence from the buffer's live cursorX/cursorY. That made the fields write-only, so removing them doesn't change output. Serializer tests pass.
• stats/app: the merge in chore: merge dev into v2 #35591 (hero redesign) removed the model-rank-panel that rendered formatModelRankMoveLabel. Its i18n keys (model.noUsageLastWeek, model.newThisWeek, model.sameAsPreviousWeek, model.vsPreviousWeek) are now unused but are left alone here. If the rank-move label should come back, that is a separate fix.
• storybook has no typecheck script, and its tsconfig already fails with unrelated errors (unresolved @/… aliases and others). The flag is added for consistency, but nothing enforces it yet.
• identity and effect-drizzle-sqlite have no tsconfig, so they are unchanged.
• noUnusedParameters is still off.

Scope

This is one of a series of PRs that turn on noUnusedLocals package by package. It only touches the packages listed above.

Verification

# each package: schema server sdk simulation enterprise http-recorder httpapi-codegen session-ui merman gui-extensions stats/{app,core,server}
bun typecheck
(cd packages/storybook && bunx tsgo -p tsconfig.json --noEmit | grep -E 'TS6(133|192|196|198)')
(cd packages/schema && bun test test/event-manifest.test.ts)
# each package: http-recorder httpapi-codegen session-ui merman gui-extensions simulation
bun run test
(cd packages/server && bun run test test/event-feed.test.ts)
bun run check

• All of these typechecks pass. Storybook reports no unused-local errors.
• Tests pass: schema 7, http-recorder 48, httpapi-codegen 96, session-ui 200, merman 504, gui-extensions 94, simulation 47, server event-feed 6. One merman timing assertion failed once and passed on rerun.
• bun run check: Tasks: 36 successful, 36 total.