audit(specify): close cycle — repair planner, grounding-check, schema drift

Architect drift review (cycle 9e8b9ec..HEAD) returned drift_found. Three
cycle-introduced items, all repaired here as tidy edits:

- planner/SKILL.md: the cycle never touched it (recon never scoped it,
  the feat commit body's "every pipeline rendering agrees" over-claimed).
  Its Handoff Contract still named `brainstorm → planner` and the bounce
  `planner → brainstorm`; the Input-source cross-ref and two
  rationalisation rows still pointed at brainstorm as the spec producer.
  All repointed to specify (specify produces and owns the spec; brainstorm
  is the optional discovery stage upstream of it). The skip rule now lists
  specify in the design path tdd bypasses.
- specify/agents/grounding-check.md: the agent move left one stale pair —
  "self-review (Step 7) and user-approval (Step 8)" were brainstorm's old
  numbers; in specify they are Step 4 and Step 6.
- profile-schema + template: the `optional: true` per-phase key I
  introduced in the plan was undocumented AND rested on a semantic error —
  `brainstorm: { gates: [specify] }` reads as "specify cannot start until
  brainstorm has run", which is false (specify enters directly from
  sources). Corrected to `brainstorm: {}` (an active phase with no hard
  gate of its own, like implement); specify keeps `gates: [planner]` as
  the one real hard gate. The optional key is gone; brainstorm's
  optionality lives in the skip rules and SKILL prose, where it belongs.

Why these escaped the cycle's own grep suite: the consistency greps used
`brainstorm *-> *planner`, which does not match the real renderings
`` `brainstorm` -> `planner` `` (backticks between the words). The same
filter-string blind spot recurred twice this session; the verification
greps here tolerate optional backticks.

Pre-existing debt (NOT cycle-introduced), filed as backlog Brummel/Skills
issue #5 rather than fixed here: docs/migration.md's layout tree and
README's migration-status both predate tdd/glossary/pseudo/issue/
postmortem and misdescribe the roster.

Verdict: cycle drift-clean after these repairs (carry-on). No regression
gate (prose repo, no scripts). Not a milestone close.

specify/agents/grounding-check.md

@@ -19,7 +19,7 @@ demands that the spec — not the plan — be corrected at the
 root.
 
 This agent is dispatched between specify's linguistic
-self-review (Step 7) and user-approval (Step 8). The
+self-review (Step 4) and user-approval (Step 6). The
 specify-driven orchestrator has spent its budget building
 the spec and is biased toward shipping it. You, by contrast,
 arrive fresh: no sunk-cost, no investment in the framing.