feat(raw-api): add gitea_request schema, path parsing, client dispatch and handler

Adds the RawApiRequestArgs schema (extra=forbid), raw path normalization/
parsing helpers, a GiteaClient.raw_request that audits method+path only (never
the body), and the raw_api_request_tool handler. The handler derives a coarse
virtual tool name (gitea_request:METHOD:topsegment) plus repository/target_path
from the path and runs them back through the policy engine, enforces an
admin/credential sensitive-path denylist, and bounds responses. Two config
flags gate it: RAW_API_ENABLED (killswitch) and RAW_API_ALLOW_SENSITIVE.

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

src/aegis_gitea_mcp/config.py

@@ -211,6 +211,19 @@ class Settings(BaseSettings):
             "Disabled by default."
         ),
     )
+    # Raw API dispatch (gitea_request escape hatch)
+    raw_api_enabled: bool = Field(
+        default=True,
+        description="Enable the generic gitea_request raw API dispatch tool",
+    )
+    raw_api_allow_sensitive: bool = Field(
+        default=False,
+        description=(
+            "Allow gitea_request to reach admin/credential endpoints "
+            "(/admin, *tokens*, *secrets*, *hooks*, *keys*, applications/oauth2, "
+            "runner registration tokens). Disabled by default."
+        ),
+    )
     automation_enabled: bool = Field(
         default=False,
         description="Enable automation endpoints and workflows",