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/backend/resolve_common.py

@@ -24,10 +24,11 @@ from ..bottle_state import (
     supervise_state_dir,
     write_metadata,
 )
-from ..egress import Egress, EgressPlan
+from ..egress import Egress, EgressPlan, egress_forge_routes
 from ..git_gate import GitGate, GitGatePlan
 from ..log import die
 from ..manifest import Manifest, ManifestBottle
+from ..manifest.forge import render_forge_guidance
 from ..supervisor.plan import SupervisePlan
 from ..orchestrator.supervisor import Supervisor
 from ..util import slugify
@@ -71,12 +72,21 @@ def write_launch_metadata(
 
 def prepare_agent_state_dir(slug: str, manifest: Manifest) -> tuple[Path, Path]:
     """Create the agent state subdir, write the prompt file.
-    Returns (agent_dir, prompt_file)."""
+    Returns (agent_dir, prompt_file).
+
+    For repositories associated with a forge, appends generated, non-secret
+    provider-specific workflow guidance to the prompt (PRD
+    prd-new-trusted-agent-forge-identity). The guidance carries neither the
+    token value nor its `token_secret` name."""
     agent = manifest.agent
     agent_dir = agent_state_dir(slug)
     agent_dir.mkdir(parents=True, exist_ok=True)
     prompt_file = agent_dir / "prompt.txt"
-    prompt_file.write_text(agent.prompt or "")
+    prompt = agent.prompt or ""
+    guidance = render_forge_guidance(manifest.forge_associations)
+    if guidance:
+        prompt = f"{prompt.rstrip()}\n\n{guidance}" if prompt.strip() else guidance
+    prompt_file.write_text(prompt)
     prompt_file.chmod(0o600)
     return agent_dir, prompt_file
 
@@ -88,11 +98,18 @@ def prepare_git_gate(bottle: ManifestBottle, slug: str) -> GitGatePlan:
 
 
 def prepare_egress(
-    bottle: ManifestBottle, slug: str, provision: AgentProvisionPlan,
+    manifest: Manifest, slug: str, provision: AgentProvisionPlan,
 ) -> EgressPlan:
+    """Build the egress plan, adding a scoped, proxy-held Gitea API route for
+    each forge alias referenced by a selected git-gate repo (PRD
+    prd-new-trusted-agent-forge-identity). The token is resolved from the host
+    env at launch and never enters the bottle."""
     egress_dir = egress_state_dir(slug)
     egress_dir.mkdir(parents=True, exist_ok=True)
-    return Egress().prepare(bottle, slug, egress_dir, provision.egress_routes)
+    forge_routes = egress_forge_routes(manifest.forge_associations)
+    return Egress().prepare(
+        manifest.bottle, slug, egress_dir, provision.egress_routes, forge_routes,
+    )
 
 
 def prepare_supervise(bottle: ManifestBottle, slug: str) -> SupervisePlan | None: