feat(specify): add spec-production entry path; split brainstorm

Add `specify` as a third co-equal entry path into the dev cycle: it
produces an approved spec from already-settled sources (an exhaustive
issue, a long in-context design discussion, or a design brainstorm just
ratified) with review but no interview. This is the producing half of a
deliberate deciding/producing split — `brainstorm` shrinks to optional
discovery, `specify` becomes the sole spec-production gate before
`planner`, mirroring the RED->GREEN split that keeps tdd/debug honest.

What moved:
- brainstorm/SKILL.md: stripped of the hard-gate, the acceptance
  criterion, write-spec, self-review, grounding-check, user-review, and
  planner-handoff steps; terminal state is now handing a ratified design
  narrative to specify. Steps renumbered 1-5 (production steps left).
- specify/SKILL.md (new): the production core, with a precondition gate
  (Step 1.5) that bounces to brainstorm the moment the sources do not
  resolve a load-bearing decision — the same discipline tdd uses.
- The grounding-check agent moved brainstorm/agents/ -> specify/agents/
  (no-orphan-agents: it lives under its dispatcher), refs repointed.
- boss/SKILL.md: Entry-path reflection is now three-way (tdd / specify /
  brainstorm). specify dispatches autonomously (bounded, no interview)
  and pauses at its user-review gate; only a fresh brainstorm cycle
  stays a pre-dispatch bounce-back.
- pipeline.md, README, profile-schema, the profile template, and the
  migration layout updated so every pipeline rendering agrees; specify
  is a CORE node (not opt-in, unlike tdd) carrying gates: [planner].

Design alternative rejected: parallel sibling skills sharing a
docs/spec-production.md (extract-to-doc). Chosen extract-and-chain
instead — the shared surface is ~70%, so a shared doc would either
become the skill body or drift; chaining keeps one executed home for the
gates.

Verification (prose repo, no test suite): the spec's internal-
consistency grep suite (no two-path drift, no direct brainstorm->planner
edge, specify referenced in every rendering, grounding-check single home
under specify, specify structural completeness) all green. Orchestrator
inspection additionally fixed two dead step-refs the plan under-scoped
(a "(Step 4)" lift-validation pointer and a "Skipping Step 7
self-review" red flag, both pointing at steps brainstorm no longer has)
and corrected six pre-existing brainstorm->planner renderings in
pipeline.md and tdd that predated this cycle.

Known follow-ups (non-blocking): the committed spec writes
`skills/specify/` in places (typo; skill dirs are repo-top-level) — to
be corrected separately. The grounding-check hard-gate was degenerate
for this very cycle (this repo has no profile and no test suite); the
skip is documented in the spec and the session.

docs/pipeline.md

@@ -4,10 +4,11 @@
 [new cycle]               [test-specifiable feature]      [bug observed]
        |                            |                            |
        v                            v                            v
- brainstorm  ->  plan  ->  implement                          debug -> implement (mini)
-       ^                            |
-       |                           tdd -> implement (mini)
-       +----(design fork)----------/   (RED executable-spec -> GREEN, like a bug fix)
+ brainstorm  ->  specify  ->  plan  ->  implement             debug -> implement (mini)
+       ^            ^               |
+       |            |              tdd -> implement (mini)
+       |       specify -> plan  (design settled in sources)
+       +----(design fork)----------/   (specify/tdd bounce here; RED executable-spec -> GREEN)
        (per iteration loop)
                   |
        [cycle close — a loop step, not a milestone close]
@@ -37,7 +38,7 @@
 These are two distinct axes, and conflating them is a bug.
 
 - A **cycle** is one round in the pipeline graph above
-  (`brainstorm → planner → implement → audit → [fieldtest]`).
+  (`brainstorm → specify → planner → implement → audit → [fieldtest]`).
   A cycle close is an internal loop step.
 - A **milestone** is a tracker container (Gitea milestone,
   GitHub milestone, Linear project — whatever the project's
@@ -85,9 +86,23 @@ close`); no skill performs it automatically.
 
 ### brainstorm
 
-Hard-gate before plan. Gathers requirements, explores 2-3
-approaches with trade-offs, presents a sectioned design with
-user approval, writes the spec to the configured `spec_dir`.
+Optional discovery front-end. Gathers requirements, explores 2-3
+approaches with trade-offs, presents a sectioned design with user
+approval, then hands the ratified design to `specify` (it writes no
+spec itself). Skipped when the design is already settled in the
+sources — that work enters through `specify` directly.
+
+### specify
+
+Hard-gate before plan — the spec-production core and the carrier of the
+"no plan without an approved spec" invariant. Takes a settled design
+(directly from sources, or a ratified design handed over by
+`brainstorm`), applies the feature-acceptance criterion, writes the
+spec to the configured `spec_dir`, runs the parse-every-block and
+`grounding-check` gates, and takes user sign-off — with review but no
+interview. Bounces to `brainstorm` the moment the sources do not
+resolve a load-bearing design decision. A core node, not opt-in
+(unlike `tdd`).
 
 ### planner
 
@@ -119,7 +134,7 @@ the GREEN side to the implement skill in mini mode.
 
 ### tdd
 
-Opt-in alternative to the `brainstorm → planner` design entry,
+Opt-in alternative to the `brainstorm → specify → planner` design entry,
 for work whose desired behaviour is test-specifiable — expressible
 as one failing test. RED-first: the `tdd-author` agent turns a
 description or issue into a single minimal, autonomous RED
@@ -172,7 +187,11 @@ Reviewer agents have role-specific states:
 Skipping is codified per skill, not ad hoc. Each `SKILL.md`
 documents what the skill skips and under what conditions:
 
-- `brainstorm` is never skipped at cycle start.
+- `specify` is never skipped at cycle start — it is the spec-production
+  gate before `planner`. `brainstorm` is the *optional* discovery stage
+  before it: skipped when the design is already settled in the sources
+  (the work enters through `specify` directly), run when a load-bearing
+  decision is still open.
 - `planner` is never skipped at iteration start, except for
   the bug-driven `debug → implement (mini)` side path.
 - `implement` is the iteration body; not skippable.