feat: operation-name normalization table with fail-closed enforcement (#106)

Promote the #103 minimal alias map to the documented public table
GITEA_OPERATION_ALIASES and add the #106 enforcement layer:

- normalize_operation(op, service): canonical namespaced names; legacy
  spellings accepted only via the explicit table; unknown, ambiguous,
  and cross-service names fail closed.
- check_operation(op, allowed, forbidden, service): normalizes BOTH the
  requested operation and the profile lists before any membership
  check; forbidden always overrides allowed; unnormalizable allowed
  entries grant nothing and unnormalizable forbidden entries deny the
  request, so normalization can never silently widen permissions;
  empty/missing allowed list denies everything.
- gitea_check_pr_eligibility now routes its capability check through
  check_operation, fixing the mismatch where canonical namespaced
  profile ops (gitea.pr.merge) never matched the raw action (merge)
  and namespaced forbidden entries were never enforced.
- Document the normalization table and enforcement rules in
  docs/gitea-execution-profiles.md, replacing the stale 'enforcement
  out of scope' caveat.
- tests/test_op_normalization.py: full #106 matrix (27 tests) —
  qualified/legacy allowed and forbidden, unknown, ambiguous, service
  mismatch, forbidden-overrides-allowed, empty/missing allowed,
  duplicates after normalization, no permission widening, and
  eligibility integration proving normalization happens before
  enforcement. Existing v1/env unqualified behaviour stays compatible.

Closes #106

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/gitea-execution-profiles.md

@@ -134,8 +134,50 @@ Rules:
   appears in both, it is forbidden.
 - An operation not present in `allowed_operations` is treated as **not
   allowed** (deny by default).
-- These categories are descriptive for this issue. Their runtime enforcement is
-  out of scope here (see roadmap links).
+
+## Operation-name normalization (#106)
+
+Canonical operation names are namespaced: `{service}.{area}.{verb}` (e.g.
+`gitea.pr.merge`, `jenkins.build.read`). Legacy unqualified spellings are
+accepted **only** through the explicit alias table below (the code of record
+is `GITEA_OPERATION_ALIASES` in `gitea_config.py`; the enforcement matrix is
+`tests/test_op_normalization.py`).
+
+| Legacy spelling   | Canonical operation        |
+|-------------------|----------------------------|
+| `read`            | `gitea.read`               |
+| `review`          | `gitea.pr.review`          |
+| `comment`         | `gitea.pr.comment`         |
+| `approve`         | `gitea.pr.approve`         |
+| `request_changes` | `gitea.pr.request_changes` |
+| `merge`           | `gitea.pr.merge`           |
+| `pr.create`       | `gitea.pr.create`          |
+| `branch.push`     | `gitea.branch.push`        |
+| `branch`          | `gitea.branch.create`      |
+| `commit`          | `gitea.repo.commit`        |
+| `push`            | `gitea.branch.push`        |
+| `open_pr`         | `gitea.pr.create`          |
+
+For non-Gitea services, a single unqualified word namespaces to the checked
+service (`read` → `jenkins.read` when checking Jenkins); names already
+prefixed with that service pass through unchanged.
+
+Enforcement rules (`gitea_config.check_operation`, run **before** any
+allowed/forbidden membership check):
+
+- Unknown operation names fail closed (denied).
+- Ambiguous names — dotted names that are neither service-prefixed nor in the
+  alias table — fail closed.
+- Cross-service names are never accepted by the wrong service
+  (`jenkins.read` never matches a Gitea check, and a Gitea alias is never
+  applied to another service).
+- `forbidden_operations` overrides `allowed_operations` after both sides are
+  normalized, so a legacy spelling can never bypass a canonical forbidden
+  entry (or vice versa).
+- An allowed entry that cannot be normalized grants nothing; a forbidden
+  entry that cannot be normalized denies the request. Normalization can
+  therefore never silently widen permissions.
+- An empty or missing `allowed_operations` list denies everything.
 
 ## Identity and fail-closed rules