skills: resolve cross-skill drift in trivial carve-out and parse-gate

Two consistency fixes across the skill suite, both found by a
prose-audit agent swarm.

Trivial-mechanical-edit carve-out: brainstorm and planner each
invented their own bound (≤30 LOC, single file) that contradicts
the canonical definition in the project's CLAUDE.md (which allows
a rename across N files and sets no LOC ceiling) and disagreed
with implement. Both now reference that carve-out instead of
restating a divergent shape.

Parse-block gate: brainstorm Step 7 and planner Step 5 spelled out
the parser-invocation protocol near-verbatim. Both now defer to
docs/profile-schema.md, which owns the protocol, and keep only
their skill-specific parts (target artefacts, failure semantics,
where the parse-trace goes) — matching the single-sourcing the
carrier contracts already use.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

brainstorm/SKILL.md

@@ -32,8 +32,8 @@ Triggers:
 
 - A bug-fix iteration (use `debug` directly).
 - A tidy iteration (use `audit` directly).
-- A trivial mechanical edit (≤1 file, ≤30 LOC, no design
-  judgement).
+- A trivial mechanical edit (per the project's CLAUDE.md
+  "trivial mechanical edits" carve-out).
 
 **Skipping is not permitted** for:
 
@@ -242,24 +242,17 @@ Inline checklist (not a subagent dispatch):
    change (plus the worked user-facing example for a surface
    cycle)? A load-bearing change described only in prose is
    a self-review failure to fix, exactly like a placeholder.
-6. **Parse-every-block gate.** If the project profile declares
-   `spec_validation.parsers`, extract every fenced code block
-   from the spec. For each block whose fence label has a
-   `parsers` entry: write the block to a temp file with the
-   entry's `ext`, run the entry's `cmd` with `{file}`
-   substituted, and require exit 0. A non-zero exit is a
+6. **Parse-every-block gate.** Extract every fenced code block
+   from the spec and run it through the `spec_validation` gate
+   defined in `docs/profile-schema.md` (which owns the
+   parser-invocation protocol, the noted no-parser skip, the
+   malformed-entry failure, and the no-op when the profile
+   declares no `spec_validation`). A parse failure here is a
    self-review failure — the spec inlines code that does not
    parse against the live tool — fix the spec before proceeding;
    do not pass the unparsed bytes downstream. Paste the
-   parse-trace (the Run block and its output) into the
-   brainstorm chat: a visible trace is what attests the gate
-   fired, and its absence means the gate was skipped. A block
-   whose fence label has no `parsers` entry is skipped and the
-   skip is noted ("no parser for fence label X"); never a silent
-   pass. A malformed entry (`cmd` without `{file}`, or `ext` /
-   `cmd` missing) is a profile error to surface, not a skip. If
-   the profile declares no `spec_validation`, this check is a
-   documented no-op.
+   parse-trace into the brainstorm chat: a visible trace attests
+   the gate fired; its absence means it was skipped.
 
 Fix issues inline. No need to re-review — fix and commit.