refactor(git): normalize rtk-prefix usage, add metadata.version

Two bundled fixes across the same nine skills, since both touch the
same files.

Issue #113: skill prose used rtk git and bare git inconsistently for
the same operations, with no stated rule for which applied where.
Executable instructed commands (a dispatch-table "Run" cell, a fenced
code-block procedure, an imperative step) now consistently use rtk
git; illustrative or referential mentions -- naming a flag's behavior,
quoting a doc heading, warning against an anti-pattern -- stay bare
git. Documented in the new plugins/git/README.md, scoped to this
plugin only: gitea-* skills talk to the server over MCP tools and
carry no git/rtk mentions at all.

Also the git-plugin slice of #127: metadata.version added to the
eight skills that lacked it. git-commits already had one and is
untouched.

Fixes: #113
Fixes: #127
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EeH8SCbcrCAQrtymkNuhKP

plugins/git/.apm/skills/git-remotes/references/fetch.md

@@ -11,19 +11,19 @@ Fetch **with no refspec** updates remote-tracking branches (`refs/remotes/<name>
 
 That safety comes from the default refspec, not from `fetch` itself. Give it an explicit one and it writes to local branches: verified on Git 2.39.5, `git fetch origin main:probe` fast-forwarded the local `probe` branch, and a `+` prefix force-updates the destination, discarding whatever commits it held. Treat any `fetch` carrying a `<src>:<dst>` refspec as a branch update, not a read.
 
-- **One remote**: `git fetch <remote>` — all branches
-- **One branch**: `git fetch <remote> <branch>` — the result lands in `FETCH_HEAD`, not a tracking ref
-- **All remotes**: `git fetch --all`
-- **Prune properly**: `git fetch --all --prune --prune-tags` cleans stale branches *and* tags
-- **Auto-prune**: `git config --global fetch.prune true` (or `remote.<name>.prune` to scope it to one remote), and `fetch.pruneTags true` for tags
+- **One remote**: `rtk git fetch <remote>` — all branches
+- **One branch**: `rtk git fetch <remote> <branch>` — the result lands in `FETCH_HEAD`, not a tracking ref
+- **All remotes**: `rtk git fetch --all`
+- **Prune properly**: `rtk git fetch --all --prune --prune-tags` cleans stale branches *and* tags
+- **Auto-prune**: `rtk git config --global fetch.prune true` (or `remote.<name>.prune` to scope it to one remote), and `fetch.pruneTags true` for tags
 
 ## Shallow and partial fetch
 
 ```bash
-git fetch --depth=<n>             # deepen history, or create a shallow clone
-git fetch --unshallow             # convert a shallow clone to full history
-git fetch --update-shallow        # allow the fetch to update the shallow boundary
-git fetch --refmap='' <remote> <branch>  # fetch without updating any tracking ref (FETCH_HEAD only)
+rtk git fetch --depth=<n>             # deepen history, or create a shallow clone
+rtk git fetch --unshallow             # convert a shallow clone to full history
+rtk git fetch --update-shallow        # allow the fetch to update the shallow boundary
+rtk git fetch --refmap='' <remote> <branch>  # fetch without updating any tracking ref (FETCH_HEAD only)
 ```
 
 ## Default fetch refspec