refactor: normalize apply statuses, remove dead code, fix signal handler

- lib/apply/index.mjs: add STATUS_MAP to normalize platform-specific statuses
  to generic ones (no_button/no_submit/no_modal → skipped_no_apply).
  Documented all generic statuses for AI/developer reference.
- job_applier.mjs: handleResult now handles skipped_no_apply, default case
  logs + saves instead of silently dropping
- lib/linkedin.mjs: remove dead applyLinkedIn() and detectAts(), clean imports
  (~110 lines removed). Search-only module now.
- lib/wellfound.mjs: remove dead applyWellfound(), clean imports.
  Search-only module now.
- lib/lock.mjs: fix async signal handler — shutdown handlers now actually
  complete before process.exit()
- test_linkedin_login.mjs: add try/catch/finally with proper browser cleanup
- README: update status table with all current statuses

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -198,10 +198,13 @@ claw-apply/
 | `applied` | Successfully submitted |
 | `needs_answer` | Blocked on unknown question, waiting for your reply |
 | `failed` | Failed after max retries |
-| `skipped` | Honeypot detected |
+| `already_applied` | Duplicate detected, previously applied |
+| `skipped_honeypot` | Honeypot question detected |
 | `skipped_recruiter_only` | LinkedIn recruiter-only listing |
-| `skipped_external_unsupported` | External ATS (Greenhouse, Lever — not yet supported) |
-| `skipped_easy_apply_unsupported` | No Easy Apply button available |
+| `skipped_external_unsupported` | External ATS (Greenhouse, Lever, etc. — stubs ready) |
+| `skipped_no_apply` | No apply button, modal, or submit found on page |
+| `stuck` | Modal progress stalled |
+| `incomplete` | Ran out of modal steps without submitting |
 
 ## Roadmap