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>

bot_bottle/cli/commands/start.py

@@ -128,7 +128,7 @@ def cmd_start(argv: list[str]) -> int:
         if not manifest.all_agent_names:
             print(
                 "bot-bottle: no agents defined. "
-                "Add an agent to ~/.bot-bottle/agents/ or ./bot-bottle/agents/ to get started.",
+                "Add an agent to ~/.bot-bottle/agents/ to get started.",
                 file=sys.stderr,
             )
             return 1
@@ -383,12 +383,9 @@ def _peek_agent_bottle(manifest: ManifestIndex, agent_name: str) -> str:
     from ...manifest.loader import scan_agent_names
     from ...yaml_subset import YamlSubsetError, parse_frontmatter
 
+    # Agents are home-only (PRD prd-new-trusted-agent-forge-identity).
     home_agents = scan_agent_names(manifest.home_md / "agents")
-    cwd_agents: dict[str, Path] = {}
-    if manifest.cwd_md is not None:
-        cwd_agents = scan_agent_names(manifest.cwd_md / "agents")
-    merged = {**home_agents, **cwd_agents}
-    path = merged.get(agent_name)
+    path = home_agents.get(agent_name)
     if path is None:
         return ""
     try:
@@ -488,13 +485,19 @@ def _manifest_to_yaml(manifest: Manifest) -> str:
         lines.append("  skills:")
         for s in agent.skills:
             lines.append(f"    - {s}")
-    if not agent.git_user.is_empty():
-        lines.append("  git-gate:")
-        lines.append("    user:")
-        if agent.git_user.name:
-            lines.append(f"      name: {agent.git_user.name}")
-        if agent.git_user.email:
-            lines.append(f"      email: {agent.git_user.email}")
+    if agent.author is not None:
+        lines.append("  author:")
+        lines.append(f"    name: {agent.author.name}")
+        lines.append(f"    email: {agent.author.email}")
+    if agent.forge_accounts:
+        lines.append("  forge-accounts:")
+        for alias, acct in sorted(agent.forge_accounts.items()):
+            lines.append(f"    {alias}:")
+            lines.append(f"      url: {acct.url}")
+            lines.append("      auth:")
+            lines.append(f"        type: {acct.auth_type}")
+            # token_secret name is host config; show the name, never a value.
+            lines.append(f"        token_secret: {acct.token_secret}")
 
     bottle = manifest.bottle
     lines.append("bottle:")
@@ -510,20 +513,14 @@ def _manifest_to_yaml(manifest: Manifest) -> str:
         for k, v in sorted(bottle.env.items()):
             lines.append(f"    {k}: {v}")
 
-    has_git_gate = not bottle.git_user.is_empty() or bottle.git
-    if has_git_gate:
+    if bottle.git:
         lines.append("  git-gate:")
-        if not bottle.git_user.is_empty():
-            lines.append("    user:")
-            if bottle.git_user.name:
-                lines.append(f"      name: {bottle.git_user.name}")
-            if bottle.git_user.email:
-                lines.append(f"      email: {bottle.git_user.email}")
-        if bottle.git:
-            lines.append("    repos:")
-            for entry in bottle.git:
-                lines.append(f"      {entry.Name}:")
-                lines.append(f"        url: {entry.Upstream}")
+        lines.append("    repos:")
+        for entry in bottle.git:
+            lines.append(f"      {entry.Name}:")
+            lines.append(f"        url: {entry.Upstream}")
+            if entry.Forge:
+                lines.append(f"        forge: {entry.Forge}")
 
     if bottle.egress.routes:
         lines.append("  egress:")