docs: trim repeated boilerplate in git, gitea, and bin skills

Finding 13: five blocks of near-identical wording were repeated across
skills within a plugin — the gitea "resolve owner and repo" step (5
skills), the 404-masks-403 note (6 files), the manual pagination
explanation (8 files), the git plugin's main/master force-push refusal
(7 files, some with multiple internal restatements), and the bin
skills' domain-glossary/ADR paragraph (5 skills). Tightened each
instance in place — same meaning, fewer words — rather than extracting
to a shared file, which ADR-0014's one-file-per-skill install
constraint rules out. Left the three git skills' structured-result
JSON shapes alone (coupled to the separate, out-of-scope git-orchestrate
merge candidate, finding 19).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YR2CjVumUbEGWcMikcoXBD

plugins/gitea/.apm/skills/gitea-labels-milestones/references/labels.md

@@ -51,8 +51,8 @@ runtime error from Gitea rather than a client-side validation error.
 label_read  method: "list_repo_labels"  owner: <owner>  repo: <repo>  per_page: 50
 ```
 
-Paginate (`page: 1, 2, ...`) until the returned count is less than `per_page`. This is the only way
-to build a complete name → ID map — there is no lookup-by-name endpoint.
+Paginate (`page: 1, 2, ...`) until the count is below `per_page` — the only way to build a complete
+name → ID map, since there's no lookup-by-name endpoint.
 
 Every returned repo label carries its own `exclusive` boolean, so exclusivity is always *readable*
 per repo label. That does not contradict `label_write`'s schema, which annotates `exclusive` as