chore(release-skill): tighten Rust-crates count and commit-list truncation

[brunopgalvao]

Summary

Three clarifications to the /release skill, caught while cutting v0.16.0 (#275).

What's changing

1. render.py — stop generating Python scripts per release

Every release until v0.16.0 produced /tmp/render_cover.py, /tmp/render_chain.py, /tmp/render_notes.py, /tmp/render_manifest.py, /tmp/render_pr_body.py as one-off scratch files with hardcoded scalars (VERSION strings, commit lists, RPC-captured values) re-typed each release. That's wasteful and — more importantly — hardcoded VERSION = "0.16.0" literals are fabricated values, violating the skill's own "no fabricated values" rule.

.claude/skills/release/render.py now ships as the single committed renderer with argparse subcommands:

Subcommand	What it does
cover	Executes the full cover.data.md contract: scalars from git, 6 variable-count fragments per the documented scaling rules, xmllint + zero-unresolved assertions.
cover-chain	Walks primary → fallback endpoints (added a User-Agent header — rpc.polkadot.io was 403'ing Python's default UA), runs the one-shot capture, writes nothing + exit 0 if every endpoint fails (per the "never fabricate, never cache-reuse" rule).
notes, manifest, pr-body	Scalars from args + git diff --shortstat; narrative markers from --summary-file / --whats-new-file / --commits-file / --breaking-file so LLM-authored prose stays separate from deterministic rendering.

End-to-end tested: all 5 subcommands produce xmllint-clean / yaml-valid outputs with zero unresolved tokens. SKILL.md now shows the render.py ... --out ... invocation in each render section instead of prescribing the substitution pipeline in prose.

2. Fix wrong commit subject in SKILL.md Phase 4

Phase 4 told the skill to commit with chore(release): vX.Y.Z, but COMMIT_CONVENTIONS.md says the subject must be Release v{VERSION} — the downstream tag regex ^Release v[0-9]+\.[0-9]+\.[0-9]+ \(#[0-9]+\)$ matches squash-merged commits on master. During the v0.16.0 cut I followed SKILL.md and committed chore(release): v0.16.0; only the PR title rescued the squash subject to Release v0.16.0 (#275). Fixed.

3. Rust crates count is now unambiguous (from the earlier commit on this branch)

The old rule — "count [package] sections across workspace Cargo.toml files" — was vague enough that v0.15.0 and v0.15.1 shipped 7 Rust crates even though the live workspace has only two members (dot/sdk + dot/cli). v0.16.0 correctly shows 2 because I interpreted the rule strictly, but the drift shouldn't depend on the renderer's judgment. The new rule is explicit about scope (workspace members only, not templates, not clones) and pins the expected answer so future drifts are obvious. render.py cmd_cover parses members = [ … ] directly, matching the documented rule.

4. @@COMMIT_LIST ≤13 case now has a truncation cap

The scaling table previously specified truncation for 14–26 commits (32 chars + …) and ≥27 commits, but said nothing for ≤13 commits. The B2 terminal panel is 444 px wide at font-size 10 (monospace), which fits about 46 chars after the │ {sha} {icon} prefix. Added subject truncated to 42 chars with …. Matches what v0.15.1 and v0.16.0 already did by eyeballing, and what render.py now enforces.

Test plan

• cover.data.md rule changes read correctly
• render.py syntax + --help parse
• render.py manifest produces valid YAML
• render.py cover-chain hits rpc.polkadot.io (UA header works) and renders a 15 KB SVG, xmllint-clean
• render.py cover renders against live git range (v0.15.1..HEAD), xmllint-clean, zero unresolved
• render.py notes substitutes scalars + reads marker files
• render.py pr-body computes stats from git diff --shortstat, embeds {{HEAD_SHA}}-pinned cover URL
• SKILL.md Phase 4 now uses Release vX.Y.Z subject per conventions
• Dry-run the next release (e.g. v0.16.1 if/when cut) through render.py end-to-end