refactor(pc-run): retrofit to the ADR-0020 context contract

Description 477 -> 211 chars, body 736 -> 367 words. Install, autoupdate,
and clean become flow files behind the Route table.

The audit found no route for 'hooks aren't running': the only pointer to
failure-patterns.md sat inside the failure path, but when hooks never fire
the manual run succeeds, so the request fell to the ambiguity default and
was masked. Restores the disclosure that install -f is not reversible by
uninstall.

plugins/git/skills/pc-run/references/sources.md

@@ -4,7 +4,7 @@
 
 - **URL:** context7:/pre-commit/pre-commit.com
 - **Description:** Official pre-commit.com documentation — installation, configuration schema, CLI reference, hook authoring, advanced features, troubleshooting
-- **Contributing files:** SKILL.md, references/failure-patterns.md
+- **Contributing files:** SKILL.md, references/install.md, references/autoupdate.md, references/clean.md, references/failure-patterns.md
 - **Research doc:** plugins/git/docs/research/docs/pre-commit/{overview,cli-reference,troubleshooting}.md
 - **Status:** `extracted`
 
@@ -12,7 +12,7 @@
 
 - **URL:** https://pre-commit.com/
 - **Description:** Pre-commit framework homepage — full docs covering install, config, CLI, hook authoring, stages, local hooks, meta hooks, hazmat helpers, CI integration
-- **Contributing files:** SKILL.md, references/failure-patterns.md
+- **Contributing files:** SKILL.md, references/install.md, references/autoupdate.md, references/clean.md, references/failure-patterns.md
 - **Research doc:** plugins/git/docs/research/docs/pre-commit/{overview,cli-reference,troubleshooting}.md
 - **Status:** `extracted`