feat: support separate Gitea MCP runtime profiles via env config (#19)

Allow the same MCP server to run as separate MCP entries, each with its
own token and profile name, so roles stay task-scoped (the profile is
the role, not the LLM).

- gitea_auth.get_profile(): reads GITEA_PROFILE_NAME,
  GITEA_ALLOWED_OPERATIONS, GITEA_BASE_URL as non-secret metadata.
  Never reads/returns/logs the token.
- gitea_whoami now surfaces the safe profile metadata (name + allowed
  operations) alongside identity; token still never exposed.
- .env.example: placeholder-only template for a runtime profile.
- .gitignore: track .env.example while keeping real .env* ignored.
- README: document multiple env-configured MCP entries.
- tests: profile defaults/parsing, token-never-included, whoami surfaces
  profile without leaking token.

One token + one profile per process. No multi-token switching in a
single runtime. No approve/merge/eligibility workflow. No
Jenkins/Ops/GlitchTip/Release/deploy behavior. No real secrets.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -123,6 +123,58 @@ The server is a standard MCP stdio server. Point your client at:
 No environment variables needed — auth is handled via macOS keychain.
 </details>
 
+<details>
+<summary><strong>Runtime profiles (multiple env-configured entries)</strong></summary>
+
+The same server can run as **separate MCP entries**, each authenticating as its
+own Gitea token and carrying its own profile name. This keeps roles task-scoped:
+*the profile is the role, not the LLM.* Point each entry at a different
+gitignored env file.
+
+```json
+{
+  "mcpServers": {
+    "gitea-tools-reviewer": {
+      "command": "/Users/jasonwalker/Development/Gitea-Tools/venv/bin/python3",
+      "args": ["/Users/jasonwalker/Development/Gitea-Tools/mcp_server.py"],
+      "env": {
+        "GITEA_PROFILE_NAME": "gitea-reviewer",
+        "GITEA_ALLOWED_OPERATIONS": "read,review,approve"
+      }
+    },
+    "gitea-tools-merger": {
+      "command": "/Users/jasonwalker/Development/Gitea-Tools/venv/bin/python3",
+      "args": ["/Users/jasonwalker/Development/Gitea-Tools/mcp_server.py"],
+      "env": {
+        "GITEA_PROFILE_NAME": "gitea-merger",
+        "GITEA_ALLOWED_OPERATIONS": "read,merge"
+      }
+    }
+  }
+}
+```
+
+Recognized environment fields (see [`.env.example`](.env.example) for placeholders):
+
+| Variable | Purpose |
+|----------|---------|
+| `GITEA_TOKEN` | API token for this runtime. Read only by the auth layer; **never** returned, logged, or committed. |
+| `GITEA_PROFILE_NAME` | Non-secret label for the running profile (e.g. `gitea-reviewer`). Surfaced by `gitea_whoami`. |
+| `GITEA_ALLOWED_OPERATIONS` | Optional, comma-separated operation categories (descriptive metadata only for now). |
+| `GITEA_BASE_URL` | Optional informational base URL. |
+
+Notes:
+
+- This provides **one token + one profile per process**. It does not implement
+  multi-token switching inside a single runtime, nor any approve/merge/eligibility
+  gating — those are later roadmap items (#13–#18).
+- Profile name and allowed operations are **metadata only**; the token value is
+  never part of any tool output. `gitea_whoami` returns the profile name so a
+  workflow can see which runtime it is talking to.
+- See [`docs/gitea-execution-profiles.md`](docs/gitea-execution-profiles.md) for
+  the full profile model.
+</details>
+
 <details>
 <summary><strong>Codex / non-MCP tools</strong></summary>