feat(manifest): trusted agent forge identity and guidance

Implements PRD prd-new-trusted-agent-forge-identity. Moves author identity
and named forge configurations onto the trusted, host-only agent definition,
and lets a bottle repository optionally associate a git-gate repo with one of
the agent's forge aliases.

- Agent-owned identity: new `author` (name/email) and `forge-accounts`
  (alias -> canonical Gitea /api/v1 origin + host `token_secret` ref) on the
  agent manifest. `author` populates the bottle's git user.name/user.email.
- Remove `git-gate.user` from both agents and bottles; fail with a migration
  pointer to `author`. `git-gate` is no longer accepted on an agent.
- Bottle git-gate repos gain optional `forge: <alias>`, resolved against the
  selected agent's forge-accounts at composition (fail-closed on unknown).
- Fail-closed Gitea API URL validation (https, no userinfo/query/fragment,
  /api/v1 base, host lowercased, trailing slash normalized, host dedup).
- Proxy-held credential: synthesize one inspected, token-authenticated egress
  route per referenced forge alias, scoped to the origin + API prefix. The
  token is resolved from the host env at launch into the egress proxy only —
  never the bottle env, prompt, gitconfig, or workspace.
- Generated, non-secret forge workflow guidance appended to the agent prompt
  for associated repos (API base, branch-backed PR flow, AGit-ref prohibition,
  mutation verification); omitted when no repo declares a forge.
- Agents become home-only: cwd `.bot-bottle/agents` no longer contributes,
  overrides, or is selectable; warned-and-ignored like cwd bottles.
- Docs: README examples, PRD 0011 supersession note, manifest schema docstring.
- Tests: new test_forge_identity suite; legacy git-gate.user/cwd tests updated
  to the agent-owned identity model.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/unit/test_manifest_extends.py

@@ -130,8 +130,10 @@ class TestExtendsEnvMerge(unittest.TestCase):
 
 
 class TestExtendsGitMerge(unittest.TestCase):
-    """git-gate.user overlays by field; git-gate.repos merges by name,
-    with same-name child entries merging field-by-field (child wins)."""
+    """git-gate.repos merges by name, with same-name child entries
+    merging field-by-field (child wins). Bottles no longer carry a user
+    identity (PRD prd-new-trusted-agent-forge-identity), so only repos
+    merging is meaningful across extends chains."""
 
     _GIT_ENTRY_A = {"url": "ssh://git@host-a/a.git", "key": {"provider": "static", "path": "/dev/null"}}
     _GIT_ENTRY_B = {"url": "ssh://git@host-b/b.git", "key": {"provider": "static", "path": "/dev/null"}}
@@ -254,13 +256,16 @@ class TestExtendsGitMerge(unittest.TestCase):
         repo_entry = next(e for e in child.git if e.Name == "repo")
         self.assertEqual("gitea", repo_entry.Key.provider)
 
-    def test_child_git_user_inherits_parent_repos(self):
+    def test_child_inherits_parent_repos_no_user_identity(self):
+        # Child omits git-gate entirely -> inherits the parent's repos.
+        # Bottles carry no user identity anymore, so git_user stays empty
+        # across the extends chain.
         m = _build(
             base={"git-gate": {"repos": {"a": self._GIT_ENTRY_A}}},
-            child={"extends": "base", "git-gate": {"user": {"name": "Child"}}},
+            child={"extends": "base"},
         )
         self.assertEqual(["a"], [e.Name for e in m.bottles["child"].git])
-        self.assertEqual("Child", m.bottles["child"].git_user.name)
+        self.assertTrue(m.bottles["child"].git_user.is_empty())
 
 
 class TestExtendsEgressMerge(unittest.TestCase):
@@ -332,48 +337,29 @@ class TestExtendsEgressMerge(unittest.TestCase):
         self.assertIn("A.EXAMPLE.COM", msg)
 
 
-class TestExtendsGitUserOverlay(unittest.TestCase):
-    """git-gate.user: per-field overlay. Each non-empty field on child
-    wins; empties fall through to parent."""
+class TestExtendsNoBottleUserIdentity(unittest.TestCase):
+    """Bottles no longer carry a user identity (PRD
+    prd-new-trusted-agent-forge-identity): identity moved to the agent's
+    `author` block. `git-gate.user` on a bottle is rejected outright, and
+    `git_user` is always empty across an extends chain."""
 
-    def test_parent_full_child_omits(self):
-        m = _build(
+    def test_bottle_git_gate_user_dies(self):
+        # A stale `git-gate.user` on a bottle fails with the migration die
+        # even inside an extends chain.
+        msg = _error_message(
+            _build,
             base={"git-gate": {"user": {"name": "Parent", "email": "p@x"}}},
             child={"extends": "base"},
         )
-        u = m.bottles["child"].git_user
-        self.assertEqual("Parent", u.name)
-        self.assertEqual("p@x", u.email)
+        self.assertIn("git-gate.user is no longer supported", msg)
 
-    def test_child_overrides_both(self):
+    def test_git_user_empty_across_chain(self):
         m = _build(
-            base={"git-gate": {"user": {"name": "Parent", "email": "p@x"}}},
-            child={
-                "extends": "base",
-                "git-gate": {"user": {"name": "Child", "email": "c@x"}},
-            },
+            base={"git-gate": {"repos": {}}},
+            child={"extends": "base"},
         )
-        u = m.bottles["child"].git_user
-        self.assertEqual("Child", u.name)
-        self.assertEqual("c@x", u.email)
-
-    def test_child_adds_email_inherits_name(self):
-        m = _build(
-            base={"git-gate": {"user": {"name": "Parent"}}},
-            child={"extends": "base", "git-gate": {"user": {"email": "c@x"}}},
-        )
-        u = m.bottles["child"].git_user
-        self.assertEqual("Parent", u.name)
-        self.assertEqual("c@x", u.email)
-
-    def test_child_overrides_only_email(self):
-        m = _build(
-            base={"git-gate": {"user": {"name": "Parent", "email": "p@x"}}},
-            child={"extends": "base", "git-gate": {"user": {"email": "c@x"}}},
-        )
-        u = m.bottles["child"].git_user
-        self.assertEqual("Parent", u.name)
-        self.assertEqual("c@x", u.email)
+        self.assertTrue(m.bottles["base"].git_user.is_empty())
+        self.assertTrue(m.bottles["child"].git_user.is_empty())
 
 
 class TestExtendsChain(unittest.TestCase):