docs(git): delete unused git plugin config file and its read steps

Finding 21: `config.example.json` (and the never-tracked
`.claude/plugins/git/config.json` it documented) was read by
git-orchestrate and git-branches but written by nothing, and the
default-inference fallback (GitHub Flow, with Gitflow inferred from a
`develop`/`release/*` branch) already covered the no-config case.
Removed the config-read step from both, updated git-workflow's
description of the orchestrator to match, dropped the now-dangling
`applied_config` field from git-orchestrate's output shape, and
deleted the config file and its stale example reference in
docs/spec/architecture.md.

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

docs/spec/architecture.md

@@ -47,7 +47,7 @@ Two compilers produce the plugin roots you see in the tree:
 - **`apm pack` compiles the manifests** (ADR-0015). Per plugin: `.claude-plugin/plugin.json` and `.github/plugin/plugin.json`, both generated from `plugins/<name>/apm.yml`. Repo-wide, from the root `apm.yml`'s `marketplace:` block: `.claude-plugin/marketplace.json` (apm's `claude` output profile) and `.agents/plugins/marketplace.json` (its `codex` profile, a differently-shaped file). Those two are the only marketplace outputs apm has profiles for — the third root manifest, `.github/plugin/marketplace.json` (Copilot CLI's legacy path), is a byte-identical mirror of the Claude one maintained by `scripts/sync-marketplace-mirror.sh` and gated by the `check-marketplace-mirror-sync` pre-push hook.
 - **`scripts/sync-plugin-content.sh` compiles the content mirror** (ADR-0017). It wraps `apm pack --format plugin` and copies the resulting bundle's flat `agents/`, `skills/`, `commands/`, `instructions/`, `extensions/`, and merged `hooks/hooks.json` back to the plugin root. Claude Code's installer convention-scans those flat paths and has no `.apm/` awareness whatsoever, so the mirror exists solely to satisfy the host's discovery contract.
 
-`.apm/` is the sole hand-edited authoring source for plugin content. An edit made in the flat mirror is discarded by the next sync and is reported as drift by the `check-plugin-content-sync` pre-push hook. Hand-authored material that is not an `.apm/` primitive — `README.md`, `docs/`, `bin/`, `sources.md`, `.mcp.json`, and per-plugin extras such as `plugins/git/config.example.json`, `plugins/gitea/references/` and `plugins/bin/evals/` — lives at the plugin **root** and is untouched by either compiler.
+`.apm/` is the sole hand-edited authoring source for plugin content. An edit made in the flat mirror is discarded by the next sync and is reported as drift by the `check-plugin-content-sync` pre-push hook. Hand-authored material that is not an `.apm/` primitive — `README.md`, `docs/`, `bin/`, `sources.md`, `.mcp.json`, and per-plugin extras such as `plugins/gitea/references/` and `plugins/bin/evals/` — lives at the plugin **root** and is untouched by either compiler.
 
 That immunity is positional, not by filename. Anything placed *inside* a mirrored directory is destroyed regardless of what it is: `sync_dir` runs `rm -rf "$dst"` before every copy, and `sync_hooks_json` does the same to `hooks/`. A hand-written `README.md` under `plugins/<name>/hooks/` or `plugins/<name>/skills/` is deleted by the next sync with no drift report, because a file with no `.apm/` counterpart is simply absent from the regenerated tree. This has already cost the repo one document — `plugins/kyberforge/hooks/README.md`, since restored to `plugins/kyberforge/docs/hooks.md`. Plugin-root documentation belongs in `docs/`.