Tasks: lock artifacts at the approval gate

Task list

[x] T1 — lock-artifacts hook (cli/the_loop/graph/hooks/feedback.py): lock on an approval classification, skip otherwise, splice front matter in place, verify the splice, record approvedBy. Req: 1.2, 1.3, 1.4. Test: unit row.
[x] T2 — graph rewiring (pdlc-work-item-loop.yaml, pdlc-contribution-loop.yaml): drop locked: true from producing nodes; add lock-artifacts to the three approval gates; update the graphs' comments. Depends on T1. Req: 1.1, 1.2, 2.1. Test: integration row.
[x] T3 — skills and commands: SKILL.md, reference/workflow.md, and the six command docs stop demanding session-owned approvals; gate-less phases proceed on shape. Req: 2.2, 2.3. Test: e2e row (no scripted pre-gate approval steps remain).
[x] T4 — tests: unit tests for T1; e2e fixtures to status: draft; gate-rejection pivots to a missing-section block; happy-path drops tasks.md from lockedBeforeImplementation. Depends on T1–T2. Req: 1.5. Test: all rows.
[x] T5 — docs: docs/capabilities/process-graph.md, spec-workflow.md, execution-log Documentation section. Depends on T2–T3. Req: 2.2. Test: markdown lint row.

mermaid

flowchart LR
  T1 --> T2 --> T4
  T1 --> T4
  T2 --> T5
  T3 --> T5
  T1 --> T3