fix(tracker): persist the application deadline end to end (#319) (#324)

The deadline is written at every moment it is provably in hand and survives
every write that follows: seen_jobs.json base field, /rank stored-value urgency
+ expiry sweep with Step 4 persistence, tracker 14th column with header-line-only
migration for existing files, /scrape-path extraction (assistant SKILL.md 1.3.2
-> 1.3.3), preserve-unparsed-fields in /outcome and /gmail-sync, notion-sync
deadline precedence. Design, scope analysis, and the folded refinements by
jakob1379 (#319, #328).

Co-authored-by: Jakob Stender Guldberg <17257805+jakob1379@users.noreply.github.com>

.claude/skills/job-scraper/SKILL.md

@@ -135,6 +135,7 @@ For each new job, do a rapid fit check (NOT the full evaluation from `04-job-eva
       "company": "...",
       "url": "...",
       "first_seen": "YYYY-MM-DD",
+      "deadline": "YYYY-MM-DD" | null,
       "fit": "high/medium/low",
       "status": "new/skipped/ranked/expired",
       "portal": "<source portal skill, e.g. jobindex-search>"
@@ -147,6 +148,8 @@ The `portal` field records which CLI skill produced the job (results are already
 
 `/rank` extends this schema additively: ranked entries also carry `rank_score` (0–100 overall score), `rank_verdict` (fit band, e.g. "strong fit"), `rank_date` (ISO date of ranking), and `strengths`/`gaps` (1-3 verbatim bullets each, copied from the scoring agent's findings). The `status` field is set to `"ranked"`. Do not drop any of these fields when re-writing entries. Entries ranked before `strengths`/`gaps` existed simply lack them; readers tolerate their absence and never backfill by guessing.
 
+`deadline` is a base field rather than a `/rank` extension: Step 2's detail fetch already extracts the application deadline, so it is written when the job is first seen and refreshed by `/rank` Step 4 when a scoring agent returns a different value. `null` means the posting states no deadline; a missing key means the entry predates this field - **never infer a deadline** from either, and never backfill by guessing.
+
 2. Only present jobs NOT already in the seen list or tracker.
 
 ### Step 4.5: Generate Referral Contact Links (High & Medium Fit Only)