refactor(#1791): ADR-1769 Phase 6 — patch migration + curated current_phase_name preserve (#1695) (#1792)

Migrate cmdStatePatch (state.cts) onto the STATE.md Transition Module substrate
and close the curated-field clobber bug class #1743/#1695 (ADR-1769, epic #1769).

- Add {kind: 'patch'} to StateTransitionIntent, with patchCore in
  src/state-transition.cts. Applies each caller-supplied {field:value} pair via
  stateReplaceField over the full content (body + frontmatter), tracking
  updated vs. failed. data.updated/data.failed mirror the CLI output shape.
- Collapse cmdStatePatch to a transitionCore dispatch. Field-name validation
  (security) and the resync-progress decision stay in the adapter.
- #1695/#1743 fix: extend the #1230 delta heuristic in readModifyWriteStateMd to
  the curated current_phase_name, table-driven via
  getFieldClassification('current_phase_name').preservation === 'preserve-always'.
  When a write does NOT change the body Phase: source line, the curated
  frontmatter value wins over syncStateFrontmatter's body re-derivation (which
  harvests a wrong parenthetical aside — #1695). begin/planned/complete-phase
  rewrite their body Phase line, so the delta does not fire for them and
  current_phase_name still advances.
- Regression: bug-1695-state-patch-clobbers-phase-name.test.cjs — unrelated
  patch preserves curated current_phase_name; patching the Phase source advances.

All 70 transition + 493 regression tests pass (state/phase/milestone + #905/#397/#3242 lineages).

Closes #1791

docs/adr/1769-state-md-transition-module.md

@@ -213,5 +213,5 @@ alongside, leave callbacks — parallel worlds don't converge (ADR-857's failure
 | 3 | `completePhase` + `phase.cts:1770` | #1784 | — |
 | 4 | `plannedPhase` + `milestoneSwitch` | #1786 | — |
 | 5 | `milestoneComplete` + `milestone.cts:352` | #1789 | — |
-| 6 | `patch` | TBD | #1743, #1695 |
+| 6 | `patch` | #1791 | #1743, #1695 |
 | 7 | `sync`, `prune`, `update` | TBD | #1760, #1761 |