refactor(forge): address PR #318 review — PR/Issue split, sqlite state, drop footer

Addresses the five review comments on PR #318:

- Split PullRequest from Issue and add a dedicated read_pr method on
  Forge/ScopedForge/GiteaForge (a PR carries merge state an issue does
  not); is_pr_open now derives from read_pr.
- Replace the JSON-file forge state with a thin swappable CRUD interface
  (ForgeStateStore) backed by SQLite (SqliteForgeStateStore) at
  ~/.bot-bottle/bot-bottle.db.
- Remove the provenance footer (provenance.py + its test): a mutable,
  unsigned PR comment is not an audit record.
- Reword the PRD: provenance is exposed via an API, not surfaced in the
  PR; document the Issue/PullRequest split and the SQLite store.

pyright clean (whole repo), pylint 10/10, 38 forge/resume unit tests pass;
no remaining refs to the removed provenance module or old JSON state API.

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

bot_bottle/contrib/gitea/client.py

@@ -20,7 +20,7 @@ import urllib.error
 import urllib.request
 from typing import Any
 
-from ..forge.base import Comment, Forge, Issue
+from ..forge.base import Comment, Forge, Issue, PullRequest
 
 # Bound every Gitea call: a hung instance must not stall the sidecar.
 _API_TIMEOUT_SECS = 30
@@ -124,6 +124,16 @@ class GiteaForge(Forge):
             state=str(raw.get("state", "")),
         )
 
+    def read_pr(self, number: int) -> PullRequest:
+        raw = self._client.get_pull(number)
+        return PullRequest(
+            number=int(raw.get("number", number)),
+            title=str(raw.get("title", "")),
+            body=str(raw.get("body", "") or ""),
+            state=str(raw.get("state", "")),
+            merged=bool(raw.get("merged", False)),
+        )
+
     def read_comments(self, number: int) -> list[Comment]:
         return [
             Comment(
@@ -154,7 +164,7 @@ class GiteaForge(Forge):
         return None
 
     def is_pr_open(self, number: int) -> bool:
-        return self._client.get_pull(number).get("state") == "open"
+        return self.read_pr(number).state == "open"
 
 
 def _read_error_body(exc: urllib.error.HTTPError) -> str: