New projects from conversation (M2.5, PR B)

- propose_project(name, purpose, decisions) in a conversation goes up for
  a go-ahead (checked: a slug, not an existing project, no trailing
  question).
- On go, the provisioning checklist (D1): a repository with a README,
  protection on its default branch, the agent as a collaborator, a build
  VM, a deploy key, and the project entry as YAML with <...> to fill in.
- On "done", the agent reads its configuration again and adds the new
  project live (build_loop_agent(load=...); only additions), then checks
  what was provided (D4, verified, not assumed): permissions and
  protection as it sees them, then on a throwaway branch with an empty
  commit, a branch push must succeed and a push to the default branch and
  merging its own PR must be refused. The check's PR is closed and its
  branch deleted. Failures are said per item; nothing starts.
- Checked: the tracking issue (the distilled decisions, carrying the new
  item's ID), and the project's item, agreed and labelled `design`, whose
  first milestone is ARCHITECTURE.md and the build plan. A conversation
  waiting on provisioning doesn't close as idle.
- The walk replays exactly from its seed (item IDs too), and event IDs
  stay unique across simulated restarts, as a server's are.
- The test config holds output to 8192 tokens, under the test key's
  per-request cost cap.

Tests: new-project unit tests (checklist and its YAML parse as config, done
before the entry, what isn't set up, a checked project's record and first
PR, an existing name), protection enforced by a hook on the fake forge,
the walk proposing projects and saying done, and an e2e new project in a
repository the test operator provisions from the agent's checklist.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/src/nisse_dev/gitea.py

@@ -261,6 +261,19 @@ class GiteaClient:
                 who = (event.get("user") or {}).get("login")
         return who
 
+    def repository(self, repo: str) -> dict[str, Any]:
+        """The repository as this account sees it, permissions included."""
+        return dict(self._request("GET", f"/repos/{repo}"))
+
+    def branch(self, repo: str, name: str) -> dict[str, Any]:
+        """A branch as this account sees it: protected, user_can_push."""
+        return dict(self._request("GET", f"/repos/{repo}/branches/{name}"))
+
+    def merge_pull_request(self, repo: str, index: int) -> None:
+        self._request(
+            "POST", f"/repos/{repo}/pulls/{index}/merge", json={"Do": "merge"}
+        )
+
     def assign_issue(self, repo: str, index: int, assignee: str) -> None:
         self._request(
             "PATCH", f"/repos/{repo}/issues/{index}", json={"assignees": [assignee]}