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/lint/.apm/skills/vale-run/references/sources.md

@@ -7,11 +7,3 @@
 - **Research doc:** plugins/lint/docs/research/docs/vale/sources.md
 - **Contributing files:** SKILL.md, references/troubleshooting.md
 - **Status:** `extracted`
-
-## house-vale-3-15-2-repro
-
-- **URL:** (house-verified — reproduced locally against the `vale` binary, not an external source)
-- **Description:** Behaviour of Vale 3.15.2 established by running it against purpose-built fixtures in this repo, where vale.sh documents nothing or documents it wrongly: `.mdx` has no built-in support and needs either `[formats] mdx = md` or an external `mdx2vast` binary (absent, the whole invocation exits 2 with `E100 [lintMDX]`), the inline-suppression form inverts between those two configurations, the `spelling` check's `ignore` paths resolve against `StylesPath` or the working directory but never against the rule file's own directory and fail silently when they resolve nowhere, `ls-config` reports styles and paths but never rules, and the `text.frontmatter.<key>` scope matrix across multi-line YAML forms.
-- **Research doc:** none — house-verified reproduction, not part of the plugin's research corpus (no `plugins/lint/docs/research/` topic file backs this entry)
-- **Contributing files:** SKILL.md, references/troubleshooting.md
-- **Status:** `extracted`