feat(graceful-handoff): 2.0 — migrate to skills/ with disable-model-invocation [skip-docs]

Step 1 of v2.0 plan. Hard cut from commands/ to skills/ per Anthropic
recommendation for new plugins. Frontmatter sets disable-model-invocation:
true and pins model: claude-sonnet-4-6. Docs (README, CLAUDE.md, root
README) deferred to Step 9 per plan.

plugins/ultraplan-local/agents/planning-orchestrator.md

@@ -320,28 +320,33 @@ If any validation fails, fix the plan before handing to Phase 6 review.
 ### Phase 5.5 — Schema self-check (REQUIRED before Phase 6)
 
 After writing the plan file, verify the output conforms to the executor's
-parser BEFORE handing to plan-critic. Use Bash to grep the plan file:
+parser BEFORE handing to plan-critic. Run the plan validator:
 
 ```bash
-# Count canonical step headings
-grep -c '^### Step [0-9]\+: ' "$plan_path"
-
-# Count manifest blocks
-grep -c '^  manifest:' "$plan_path"
-
-# Detect forbidden narrative formats
-grep -cE '^(##|###) (Fase|Phase|Stage) [0-9]' "$plan_path"
+node ${CLAUDE_PLUGIN_ROOT}/lib/validators/plan-validator.mjs --strict --json "$plan_path"
 ```
 
-**Pass criteria:**
-- Step count ≥ 1
-- Manifest count == Step count
-- Forbidden narrative count == 0
+**Pass criteria:** validator exits 0 with `valid: true` in its JSON output.
+Internally the validator enforces (same checks as before, now in one place):
+- Step count ≥ 1, numbering is 1..N contiguous
+- Per-step Manifest YAML present, parses, and `commit_message_pattern` compiles
+- Step count == manifest count
+- Zero forbidden narrative headings (`### Fase N`, `### Phase N`, `### Stage N`,
+  `### Steg N`)
+- `plan_version: 1.7` declared (warning only if older / missing)
 
-**If the plan fails schema self-check:** rewrite the Implementation Plan
-section using the exact literal template shown earlier in Phase 5. Do NOT
-proceed to Phase 6 with a schema-failing plan — plan-critic cannot repair
-format drift, only content issues.
+Each error has a `code` field — read these to localize the fix. Common codes:
+- `PLAN_FORBIDDEN_HEADING` — narrative drift; rewrite the section using the
+  literal template from Phase 5
+- `PLAN_MANIFEST_COUNT_MISMATCH` — at least one step lost its manifest block
+- `MANIFEST_PATTERN_INVALID` — a `commit_message_pattern` does not compile;
+  check escaping (use `\\(` not `\(` in YAML double-quoted strings)
+- `PLAN_STEP_NUMBERING` — steps skip a number; renumber sequentially
+
+**If the plan fails schema self-check:** rewrite the offending section using
+the exact literal template shown earlier in Phase 5. Do NOT proceed to Phase 6
+with a schema-failing plan — plan-critic cannot repair format drift, only
+content issues.
 
 ### Failure recovery (REQUIRED for every step)