fix(phase-runner): add research gate to block planning on unresolved open questions (#1618)

* chore: add v1.31.0 npm known-issue notice to issue template config

Adds a top-priority contact link to the issue template chooser so users
are redirected to the Discussions announcement before opening a duplicate
issue about v1.31.0 not being on npm.

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

* fix(phase-runner): add research gate to block planning on unresolved open questions (#1602)

Plan-phase could proceed to planning even when RESEARCH.md had unresolved
open questions in its ## Open Questions section. This caused agents to
plan and execute with fundamental design decisions still undecided.

- Add `research-gate.ts` with pure `checkResearchGate()` function that
  parses RESEARCH.md for unresolved open questions
- Integrate gate into PhaseRunner between research (step 2) and plan
  (step 3) using existing `invokeBlockerCallback` pattern
- Add Dimension 11 (Research Resolution) to gsd-plan-checker.md agent
- Gate passes when: no Open Questions section, section has (RESOLVED)
  suffix, all individual questions marked RESOLVED, or section is empty
- Gate fires `onBlockerDecision` callback with PhaseStepType.Research
  and lists the unresolved questions in the error message
- Auto-approves (skip) when no callback registered (headless mode)
- 18 new tests: 13 unit tests for checkResearchGate, 5 integration
  tests for PhaseRunner research gate behavior

Closes #1602

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

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

agents/gsd-plan-checker.md

@@ -478,6 +478,45 @@ issue:
   fix_hint: "Add eslint verification step to each task's <verify> block"
 ```
 
+## Dimension 11: Research Resolution (#1602)
+
+**Question:** Are all research questions resolved before planning proceeds?
+
+**Skip if:** No RESEARCH.md exists for this phase.
+
+**Process:**
+1. Read the phase's RESEARCH.md file
+2. Search for a `## Open Questions` section
+3. If section heading has `(RESOLVED)` suffix → PASS
+4. If section exists: check each listed question for inline `RESOLVED` marker
+5. FAIL if any question lacks a resolution
+
+**Red flags:**
+- RESEARCH.md has `## Open Questions` section without `(RESOLVED)` suffix
+- Individual questions listed without resolution status
+- Prose-style open questions that haven't been addressed
+
+**Example — unresolved questions:**
+```yaml
+issue:
+  dimension: research_resolution
+  severity: blocker
+  description: "RESEARCH.md has unresolved open questions"
+  file: "01-RESEARCH.md"
+  unresolved_questions:
+    - "Hash prefix — keep or change?"
+    - "Cache TTL — what duration?"
+  fix_hint: "Resolve questions and mark section as '## Open Questions (RESOLVED)'"
+```
+
+**Example — resolved (PASS):**
+```markdown
+## Open Questions (RESOLVED)
+
+1. **Hash prefix** — RESOLVED: Use "guest_contract:"
+2. **Cache TTL** — RESOLVED: 5 minutes with Redis
+```
+
 </verification_dimensions>
 
 <verification_process>