feat: add read-only gitea_get_profile discovery tool (#13)

Add a read-only MCP tool that reports the active runtime execution
profile so an LLM can inspect what the current process is configured to
do before deciding whether to attempt an action later.

- gitea_get_profile: returns profile_name, allowed/forbidden operation
  categories, audit_label, token_source_name (a NAME, never a value),
  base_url, remote, resolved server, and — optionally — the verified
  authenticated username. Identity resolution fails soft and marks
  identity_status (verified/unknown/unavailable/not_resolved); the
  profile config is always returned. Never mutates Gitea.
- gitea_auth.get_profile(): extended with forbidden_operations,
  audit_label, token_source_name from env (non-secret metadata).
- .env.example / README: document the new optional metadata vars and
  the discovery tool.
- tests: metadata parsing, verified/unavailable/unknown identity paths,
  skip-identity, and secret-redaction.

Read-only. No token exposure. No multi-token switching. No PR
eligibility, review, or merge workflow. No Jenkins/Ops/GlitchTip/
Release/deploy behavior.

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

README.md

@@ -51,6 +51,7 @@ Any MCP-compatible agent (Antigravity, Claude Code, etc.) can call these tools n
 | `gitea_list_issues` | List issues with state/label filters |
 | `gitea_view_issue` | Get full details of a single issue |
 | `gitea_whoami` | Read-only: identify the authenticated Gitea account (safe metadata only) |
+| `gitea_get_profile` | Read-only: describe the active runtime execution profile (safe metadata only) |
 | `gitea_mark_issue` | Claim/release an issue (start/done) |
 | `gitea_list_labels` | List all available labels in a repository |
 | `gitea_create_label` | Create a new label with custom color |
@@ -161,16 +162,20 @@ Recognized environment fields (see [`.env.example`](.env.example) for placeholde
 | `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_FORBIDDEN_OPERATIONS` | Optional, comma-separated categories this profile must not perform (descriptive). |
+| `GITEA_AUDIT_LABEL` | Optional short label for this runtime, for audit purposes. |
+| `GITEA_TOKEN_SOURCE` | Optional *name* of the token source (e.g. an env var name). A name only — never the token value. |
 | `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).
+  gating — those are later roadmap items (#14–#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.
+  never part of any tool output. `gitea_whoami` returns the profile name, and
+  `gitea_get_profile` returns the full non-secret profile metadata so a workflow
+  can inspect which runtime it is talking to before deciding to act.
 - See [`docs/gitea-execution-profiles.md`](docs/gitea-execution-profiles.md) for
   the full profile model.
 </details>