chore(config): superpowers citers by bare name, routing map, docs, settings

Every superpowers-prefixed skill call in ship-feature, init-project, tour,
deploy, audit-delta, plugin-advisor and lib/analyze-before-plan now names
the vendored skill directly. finishing-a-development-branch is described
as the upstream skill this config does not vendor (gitflow finish is the
integration path). CLAUDE.global.md Skill routing maps the four
non-vendored skills the vendored text still references. settings.json
loses the plugin key and its marketplace block; README, USAGE,
plugin-advisor and the profile skill describe superpowers as vendored
skills, always on, zero plugin cost. CHANGELOG entry with a known
residual.

skills/audit-delta/SKILL.md

@@ -318,7 +318,8 @@ Then offer to capitalize (per CLAUDE.md): recurring finding patterns →
 
 ## TDD note (skill itself)
 
-Baseline-tested per superpowers:writing-skills (2026-06-11, isolated
+Baseline-tested per writing-skills (vendored superpowers skill;
+2026-06-11, isolated
 worktree, no skill): the agent (1) guessed the boundary from the most
 recent file date in `.claude/audits/` — wrong file, date-based; (2) wrote
 its checkpoint as prose in a dated report — unparseable next run; (3) kept