feat(forge): forge library layer for native integration (PRD chunks 1-3, 5)

Implements the bot-bottle side of the forge-native PRD that is
self-contained in this repo (the forge sidecar and orchestrate command
belong to the separate bot-bottle-orchestrator, a PRD non-goal):

- contrib/forge/base.py: Forge ABC + ScopedForge enforcing the
  read-anywhere / write-scoped model (writes rejected outside the
  assigned issue/PRs via ForgeScopeError).
- contrib/gitea/client.py: GiteaClient (stdlib-only HTTP, mirrors the
  deploy-key provisioner) + GiteaForge. Token held by the caller (the
  sidecar), not injected by cred-proxy.
- contrib/gitea/forge_state.py: ForgeState dataclass + atomic
  read/write/delete/all under ~/.bot-bottle/forge/<owner>/<repo>/.
- contrib/gitea/provenance.py: build_provenance_footer — collapsed
  markdown audit footer; watchdog/gitleaks/egress rendering.
- cli/resume.py: `resume --headless --prompt` reusing the shipped
  assume_yes + headless_prompt launch core (the new half of chunk 1).

47 new unit tests; pylint 9.98/10, pyright clean. Forge sidecar (chunk
4), orchestrate command (chunk 6), and forge_env plumbing are deferred:
their only consumer is the separate orchestrator and they are untestable
in isolation here.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WL77TgFxKbs3cidGMG9dz7

tests/unit/test_contrib_gitea_provenance.py

@@ -0,0 +1,81 @@
+"""Unit: provenance footer (PRD forge-native-integration)."""
+
+from __future__ import annotations
+
+import unittest
+
+from bot_bottle.contrib.gitea.provenance import build_provenance_footer
+
+
+def _footer(slug: str = "implementer-abc12", **over) -> str:
+    base = {
+        "agent_name": "implementer",
+        "bottle_names": ("claude",),
+        "started_at": "2026-06-29T12:00:00-04:00",
+        "finished_at": "2026-06-29T12:04:12-04:00",
+        "exit_code": 0,
+    }
+    base.update(over)
+    return build_provenance_footer(slug, **base)
+
+
+class ProvenanceTest(unittest.TestCase):
+    def test_required_fields_present(self):
+        out = _footer()
+        for token in ("Run provenance", "`implementer`", "`claude`",
+                      "`implementer-abc12`", "| exit | 0 ✓ |"):
+            self.assertIn(token, out)
+
+    def test_collapsed_details_block(self):
+        out = _footer()
+        self.assertTrue(out.startswith("<details>"))
+        self.assertIn("</details>", out)
+
+    def test_duration_minutes_seconds(self):
+        self.assertIn("| duration | 4m 12s |", _footer())
+
+    def test_duration_under_a_minute(self):
+        out = _footer(finished_at="2026-06-29T12:00:30-04:00")
+        self.assertIn("| duration | 30s |", out)
+
+    def test_duration_unknown_on_bad_timestamp(self):
+        out = _footer(finished_at="not-a-time")
+        self.assertIn("| duration | unknown |", out)
+
+    def test_nonzero_exit_marked(self):
+        self.assertIn("| exit | 1 ✗ |", _footer(exit_code=1))
+
+    def test_watchdog_changes_done_signal_row(self):
+        normal = _footer()
+        self.assertIn("sidecar `signal_done`", normal)
+        fired = _footer(watchdog_fired=True)
+        self.assertIn("watchdog — agent did not signal", fired)
+        self.assertNotIn("sidecar `signal_done`", fired)
+
+    def test_gitleaks_states(self):
+        self.assertIn("not run", _footer())
+        self.assertIn("✓ no secrets detected", _footer(gitleaks_clean=True))
+        self.assertIn("✗ secrets detected", _footer(gitleaks_clean=False))
+
+    def test_egress_omitted_when_absent(self):
+        self.assertNotIn("**Egress**", _footer())
+
+    def test_egress_rendered_when_present(self):
+        out = _footer(egress_routes=[
+            "`api.anthropic.com` — Bearer auth",
+            "`pypi.org` — unauthenticated",
+        ])
+        self.assertIn("**Egress** (deny-by-default; 2 routes allowed)", out)
+        self.assertIn("- `api.anthropic.com` — Bearer auth", out)
+
+    def test_egress_singular_route(self):
+        out = _footer(egress_routes=["`api.anthropic.com` — Bearer auth"])
+        self.assertIn("1 route allowed", out)
+
+    def test_multiple_bottles_listed(self):
+        out = _footer(bottle_names=("claude", "dev"))
+        self.assertIn("`claude`, `dev`", out)
+
+
+if __name__ == "__main__":
+    unittest.main()