chore(miner): migrate foundational, most-depended-on packages/loopover-miner/lib modules to TypeScript (batch 4.3 of 8 (Phase 4))

[JSONbored]

Problem

#7290 proposed migrating packages/loopover-miner/lib/** to TypeScript, phased for gate safety.
Phase 1 (#7299) landed the tsc build pipeline. This issue is batch 4.3 of 8 (Phase 4): convert this batch's
files, using the same in-place-emit pattern Phase 1 already wired up.

Proposal

Convert these files (and their hand-maintained .d.ts siblings) from .js to real .ts:

• lib/replay-objective-anchor.js
• lib/rejection-signal.js
• lib/replay-task-generation.js
• lib/replay-snapshot.js
• lib/laptop-init.js
• lib/governor-kill-switch.js
• lib/governor-chokepoint.js
• lib/miner-goal-spec.js

No tsconfig.json changes are needed -- its existing include glob (bin//*.ts, lib//*.ts)
picks up newly-converted files automatically.

Deliverables

• All files in this batch converted from .js to .ts
• Each file's hand-maintained .d.ts sibling removed (tsc regenerates it)

Test Coverage Requirements

No behavior change from this migration alone. Existing tests for these modules must continue to
pass unmodified (only import paths/build output shape might need adjustment).

Expected Outcome

These files are real, compiler-verified TypeScript with zero behavior change.

Links & Resources

• chore(miner): migrate packages/loopover-miner from plain .js + hand-maintained .d.ts to real TypeScript #7290 -- the parent migration proposal and phasing plan
• chore(miner): add a real tsc build pipeline for loopover-miner (#7290) #7299 -- Phase 1: the tsc build pipeline + first converted file

[linear-code]

JSO-5107