feat(planning): hedged decision kind and unticked-commitment gate on the interview page

[kyle-sexton]

Problem

Two gaps in the interview page's commitment handling, to be built together.

1. The page has no hedged decision kind. The skill records a conditional accept as hedged (skills/interview/context/surface.md:132), but hedged appears nowhere in surface/round.py, exporters.py or index.html. A hedged reply reaches the ledger only as own text (free-text: hedged: ..., exporters.py:203-204).
2. The register gate grades a page export clean while commitments are unticked. The exported register carries confirmed commitments only (exporters.py:547-590); unconfirmed ones reach the Brief as named risks (exporters.py:629-655), never as open rows, so scripts/check-open-questions.sh has nothing to grade.

Blocked on

Blocked on #4611 (ledger row grammar, PR #5470). Do not start before that merges: the ledger grammar decides how a hedged decision and an unticked commitment are written.

Evidence

• Finding 9 of the fix(planning): interview page surface defects from a live session (layout, commitments, sync, wake cost) #5191 repro (planning 0.46.0): accepted questions kept unticked commitments and the accepted card shows no indicator. The wrap-up view has commitment checkboxes and "Confirm all (N)" (plugins/planning/surface/index.html:751-752, :1012-1020, :1401; confirm-commitments op at round.py:628), but acceptance does not confirm commitments.
• Finding 17: a stale commitment survives a revision into the export. revise never writes commits (round.py:441-498, :1452-1454; only cmd_add does, round.py:772), so the old text reaches exporters.py:629-655 as a live named risk. The write-path gap is fix(planning): let interview revise update a question's commitments #5452.
• export-brief carried 21 commitments as "unconfirmed, named risks" (exporters.py:629-655).
• The separate acceptance-criteria gap at exporters.py:647-651 is fix(planning): route interview acceptance criteria into export-brief #5461 and is out of scope here.

Proposed approach

• Add a hedged decision kind that exports as its own resolution with the condition text.
• Add a gate rule: an accepted or hedged row with an unticked commitment grades as open in lock.

Acceptance criteria

• A hedged decision can be recorded on the page and exports as its own resolution carrying the condition text.
• lock grades an accepted or hedged row with an unticked commitment as open.
• Tests cover both, including a stale commitment after revise (with fix(planning): let interview revise update a question's commitments #5452).
• tests/interview-defenses.test.sh digests re-pinned if skill text changes.

Context

Refs #4653 (owner decision 2026-09-29, Option B, items 1 and 2). Blocked on #4611 (PR #5470). Related: #5191, #5452, #5461, #4474, #4423.