Add Forgejo edit/refresh sync path for space content (T05)

Keep git as source of truth: deep-link to Forgejo editor, manual refresh to
drop cache, and optional signed push webhook for automatic invalidation.

coulomb_social/apps/spaces/content.py

@@ -189,3 +189,56 @@ _FETCH_CACHE: dict[tuple[str, str, str, str, str], FetchedFile] = {}
 
 def clear_content_cache() -> None:
     _FETCH_CACHE.clear()
+
+
+def clear_content_cache_for_repo(owner: str, repo: str) -> int:
+    """Drop cached files for one Forgejo repo. Returns number of entries removed."""
+    owner = (owner or "").strip()
+    repo = (repo or "").strip()
+    if not owner or not repo:
+        return 0
+    victims = [k for k in _FETCH_CACHE if k[0] == owner and k[1] == repo]
+    for key in victims:
+        del _FETCH_CACHE[key]
+    return len(victims)
+
+
+def clear_content_cache_for_space(space: Space) -> int:
+    if not space.has_content_binding:
+        return 0
+    return clear_content_cache_for_repo(space.forgejo_owner, space.forgejo_repo)
+
+
+def forgejo_repo_url(space: Space) -> str:
+    base = (getattr(settings, "FORGEJO_BASE_URL", None) or "").rstrip("/")
+    if not space.has_content_binding or not base:
+        return ""
+    return f"{base}/{space.forgejo_owner}/{space.forgejo_repo}"
+
+
+def forgejo_edit_url(space: Space, page: str | None = None) -> str:
+    """Deep-link to Forgejo's file editor for the page markdown (git remains SoR)."""
+    base = forgejo_repo_url(space)
+    if not base:
+        return ""
+    try:
+        page_slug = normalize_page_slug(page)
+        path = page_path_for(space, page_slug)
+    except ContentFetchError:
+        return base
+    branch = space.default_branch or "main"
+    # Gitea/Forgejo: /{owner}/{repo}/_edit/{branch}/{path}
+    return f"{base}/_edit/{branch}/{path}"
+
+
+def forgejo_blob_url(space: Space, page: str | None = None) -> str:
+    base = forgejo_repo_url(space)
+    if not base:
+        return ""
+    try:
+        page_slug = normalize_page_slug(page)
+        path = page_path_for(space, page_slug)
+    except ContentFetchError:
+        return base
+    branch = space.default_branch or "main"
+    return f"{base}/src/branch/{branch}/{path}"