feat(drive): add exclude rule scanning

[pocketsharkk]

WSPC Todo

• Ticket: Parse Drive exclude rules and prune local scans (tod_01KY997DBC8PFJJKYFJ6S5EJ95)
• Source todo: Add Drive sync exclude rules (tod_01KY981JSZ4PQ234RX32ANKXRK)
• Spec: WSPC Add Drive sync exclude rules (tod_01KY981JSZ4PQ234RX32ANKXRK)

Summary

• add a validated .wspc-drive/ignore parser and case-sensitive exact/directory matcher
• exclude matching files and prune matching directories during full scans
• remove excluded file entries from incremental scan caches without conflating file and directory rules
• add the approved Drive exclude design spec and TDD regression coverage

Test Plan

• npm test -- test/handwritten/drive/exclude-rules.test.ts test/handwritten/drive/scanner.test.ts
• npm run typecheck
• CHOKIDAR_USEPOLLING=1 env -u NO_COLOR TERM=xterm-256color npm test
• npm run build
• git diff --check