docs(provenance): migrate the corpus to the Research registry grammar

Repoint every `Research doc:` at the plugin's Research registry
(git/sources.md, pre-commit/sources.md, gitea/sources.md,
agentsmd/sources.md), keeping the old topic-doc link as a parenthetical
`(digest: ...)` annotation. Brace expansions and the gitea-releases
semicolon pair collapse to one path.

Entries with no registry (org-commit-conventions, org-git-conventions,
governance-secrets-hard-prohibition, adr-0002-0003-two-tier-claude-md)
now declare `none` plus `Basis:` bullets. The two git entries cite
core/instructions/git.md and commits.md as `(removed in 5deed07)`.

Remove the house-vale-3-15-2-repro entry and its source_keys citations
from vale-config and vale-run. It claimed six behaviours were reproduced
against purpose-built fixtures in this repo, but the entry was added in
d1afdbe with no test or fixture files, and none exists in history. The
behavioural rules stay; only the unbacked provenance claim goes.

Refs: #121
ADR: 0028
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EGHFJextYtVQseaHPDDhxB

plugins/git/.apm/skills/git-workflow/references/sources.md

@@ -9,7 +9,7 @@
 
 **Source:** https://nvie.com/posts/a-successful-git-branching-model/
 
-- **Research doc:** plugins/git/docs/research/docs/git/gitflow.md (whole-document reference)
+- **Research doc:** plugins/git/docs/research/docs/git/sources.md (digest: plugins/git/docs/research/docs/git/gitflow.md — whole-document reference)
 
 **Contributing files:**
 - SKILL.md (Interaction style — branching-model-aware tips)
@@ -20,7 +20,7 @@
 
 **Source:** https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow
 
-- **Research doc:** plugins/git/docs/research/docs/git/gitflow.md (whole-document reference)
+- **Research doc:** plugins/git/docs/research/docs/git/sources.md (digest: plugins/git/docs/research/docs/git/gitflow.md — whole-document reference)
 
 **Contributing files:**
 - SKILL.md (Interaction style — branching-model-aware tips)
@@ -31,7 +31,7 @@
 
 **Source:** https://danielkummer.github.io/git-flow-cheatsheet/
 
-- **Research doc:** plugins/git/docs/research/docs/git/gitflow.md (whole-document reference)
+- **Research doc:** plugins/git/docs/research/docs/git/sources.md (digest: plugins/git/docs/research/docs/git/gitflow.md — whole-document reference)
 
 **Contributing files:**
 - SKILL.md (Interaction style — branching-model-aware tips)
@@ -42,7 +42,7 @@
 
 **Source:** context7:/git/htmldocs
 
-- **Research doc:** plugins/git/docs/research/docs/git/overview.md (whole-document reference)
+- **Research doc:** plugins/git/docs/research/docs/git/sources.md (digest: plugins/git/docs/research/docs/git/overview.md — whole-document reference)
 
 **Contributing files:**
 - SKILL.md (Workflow — general git operation vocabulary)
@@ -53,7 +53,8 @@
 
 **Source:** org-internal (formerly `core/instructions/git.md` in this repo, prior to its removal)
 
-- **Research doc:** none — org convention, not part of the plugin's research corpus (no `plugins/git/docs/research/` topic file backs this entry)
+- **Research doc:** none
+- **Basis:** core/instructions/git.md (removed in 5deed07)
 
 **Contributing files:**
 - references/hard-rules.md (whole file — the eight hard rules and the conflict-handling rule)