Slice 5: Gitea forge - PRs and Merge & clean up

New internal/forge (provider-abstracted, Gitea impl via code.gitea.io/sdk/gitea) with tested remote-URL parsing and read+write ops: list open PRs, and merge-and-cleanup (squash-merge + delete head branch when head/base share a repo). Service resolves repo->owner/repo from remotes (prefers origin) and records a pr-merged event; config gains GITEA_URL/GITEA_TOKEN (forge disabled without both). MCP tools list_prs and merge_and_cleanup_pr (merge tool tells Claude to confirm first, 1.4). HTTP GET /api/repo/prs, POST /api/repo/pr/merge. New <pr-list> component with a confirming Merge & clean up button, hidden when no forge. Verified graceful-disabled path; real merge pending token + a designated PR.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/config/config.go

@@ -34,8 +34,10 @@ type Config struct {
 	Dev     bool   // readable console logging vs structured JSON
 	LogFile string // optional file to also append logs to
 
-	GitHubToken string // optional forge token (AGENT.md §8)
-	GitLabToken string // optional forge token (AGENT.md §8)
+	GiteaURL    string // Gitea/Forgejo base URL (e.g. https://git.nilles.net)
+	GiteaToken  string // Gitea token (read + PR write + branch delete) — §8.4
+	GitHubToken string // optional forge token (later provider)
+	GitLabToken string // optional forge token (later provider)
 }
 
 // Load reads .env (if present) then the environment, applying defaults.
@@ -55,6 +57,8 @@ func Load() (Config, error) {
 		ScanFetchEnabled: envBool("SCAN_FETCH_ENABLED", false),
 		Dev:              strings.EqualFold(env("APP_ENV", "dev"), "dev"),
 		LogFile:          env("LOG_FILE", ""),
+		GiteaURL:         env("GITEA_URL", ""),
+		GiteaToken:       env("GITEA_TOKEN", ""),
 		GitHubToken:      env("GITHUB_TOKEN", ""),
 		GitLabToken:      env("GITLAB_TOKEN", ""),
 	}