Implement LinkedIn research safety PRD (US-001..US-011)

[Deviad]

Plan of record: tasks/prd-linkedin-research-safety.md (baseline a7054d7 on branch issue-7, already merged to main as cc72ca3).

Wave schedule and story-to-wave mapping, per PRD section 6 "Conservative schedule for a wave runner":

Wave	Stories	Graph run
Baseline	US-001 runtime inventory + frozen contracts	run 1
Parallel foundations	US-002 backfill stop, US-006 CV-evidence scoring, US-008 sponsor register, US-007 isolated prep	run 2
Durable access gate	US-003	run 3
Coordination + role sponsorship	US-004, US-009	run 4
Shared posting reuse	US-005	run 5
Salary integration	US-007	run 6
Combined report	US-010	run 7
Integrated verification	US-011	run 8

Constraints carried from the PRD:

• No LinkedIn access of any kind during implementation, including diagnostics.
• Each story acceptance criteria are the gate; progress checkboxes are updated in the PRD with named evidence.
• Private evidence lives under $JOBHUNTER_HOME/runs/<run-id>/research-safety/, never in published fixtures.
• Workers own disjoint writable paths; every non-owned path is read-only.
• jh-migrate.mjs has one owner at a time: US-003, then US-009, then US-005.
• Multi-agent execution route: Delegate Graph (pi-agent-wave) through Herdr, one visible tab per worker.