refactor(git-remotes): retrofit to the ADR-0020 context contract

Description 582 -> 237 chars, body 1217 -> 290 words. The single remotes.md
splits into config, fetch, push, and pull flow files.

Restores the confirm: true token to the force-push gate -- it is the git
plugin's cross-skill contract, gated on by git-orchestrate and git-branches.
Moves push.md's worked example off main, which the skill's own Step 1
refuses, and restores the never-bare---force directive.

plugins/git/skills/git-remotes/references/remote-config.md

@@ -0,0 +1,39 @@
+---
+topic: remote-config
+source_keys:
+  - git-scm-remote-docs
+  - context7-git-htmldocs
+---
+
+# Remote configuration
+
+Which remotes exist, where they point, and what they track.
+
+`git remote show <name>` needs network access — use `-n` for cached data offline, or `git remote -v`, which lists URLs without querying.
+
+## Add, remove, rename, inspect
+
+- **Add**: `git remote add <name> <url>`, or `-f` to fetch immediately
+- **Remove**: `git remote remove <name>` — deletes the remote, all its tracking refs, and its config
+- **Rename**: `git remote rename <old> <new>`
+- **Inspect**: `git remote -v` (URLs, offline) or `git remote show <name>` (live tracking status)
+- **Effective URLs**: `git remote get-url <name>` shows the URL after `insteadOf` rewrites; `git remote get-url --push --all <name>` lists every push URL
+
+## Tracking, mirroring, housekeeping
+
+- **Track one branch**: `git remote add -t <branch> <name> <url>` (repeatable); `--no-tags` suppresses tag import entirely
+- **Mirror**: `--mirror=fetch` mirrors all refs locally (bare repos only); `--mirror=push` makes every push behave like `--mirror`
+- **Prune stale tracking refs without fetching**: `git remote prune <name>`, with `--dry-run` to preview
+- **Default branch pointer**: `git remote set-head <name> -a` (auto-detect, needs a prior fetch), `... <branch>` (explicit), `... -d` (delete `refs/remotes/<name>/HEAD`)
+
+## `set-url` — full form
+
+```bash
+git remote set-url <name> <newurl>                  # replace the first fetch URL
+git remote set-url <name> <newurl> <oldurl-regex>   # replace only the URL matching regex
+git remote set-url --push <name> <url>              # change push URL only (must point at same repo)
+git remote set-url --add <name> <url>               # add an extra push URL (push to multiple remotes)
+git remote set-url --delete <name> <regex>          # remove URLs matching regex
+```
+
+`--push` changes only where pushes go — fetch and push URLs must still reference the same repository. For genuine fetch-from-A / push-to-B workflows, use two separate named remotes instead; `--push` cannot do this.