refactor: rewrite batch processor [ANK-377]

[piazza-bot]

Summary

• Replaced fixed-size batch chunks with a refill worker pool so free workers immediately take the next note.
• Threaded cancellation through batch/note processing while keeping local-server generateNotes isolated from stale manual UI cancellation.
• Made local-server generateNotes preflight note/deck mapping before worker execution and return partial results with Out of credits when the worker pool hits capacity.
• Preserved deterministic result ordering and added worker fatal-error draining so unexpected worker-loop failures do not return while sibling workers keep running in the background.

Verification

• source .venv/bin/activate && ./scripts/build.sh fix
  • Result: 83 files left unchanged; all checks passed.
• source .venv/bin/activate && ./scripts/build.sh check
  • Result: formatting/static checks passed with 0 errors, 0 warnings, 0 informations.
• source .venv/bin/activate && python -m pytest
  • Result: 142 passed.
• Architecture-review subagent loop:
  • Initial passes found worker out-of-credits/admission/fatal-drain issues; addressed them.
  • Final pass reported no actionable architecture/design issues.
• Anki sandbox E2E on this branch via source .venv/bin/activate && ./scripts/build.sh sandbox-local:
  • Smart Notes loaded successfully and started the local server on 127.0.0.1:8766.
  • Used AnkiConnect to verify version 6, read Basic model fields, create a temporary note, read it back, and delete it.
  • Used Smart Notes local server to verify ping, getSmartFields for Basic, and generateNotes on the temporary note.
  • Observed expected result for no Smart Fields: {"updated": [], "failed": [], "skipped": [<temp note id>]} with no error.
  • Shutdown left ports 8765 and 8766 closed.
  • Note: AnkiConnect printed its known requireReset() is obsolete; please use CollectionOp() warning during addNote; Smart Notes requests completed with HTTP 200.
• Computer Use visual sanity check:
  • get_app_state attached to /Applications/Anki.app and showed the sandbox Anki deck list.
  • No screenshot is included because ANK-377 changes processing/local-server behavior rather than a visual UI surface.

Agent session metadata

• Working directory: /Users/michaelpiazza/conductor/workspaces/smart_notes_all/warsaw/anki-smart-notes
• Session ID: b77430b7-3079-4a90-b0a2-ce65f0b1115a

[linear]

ANK-377