fix: Replace Codeberg dependency with local Forgejo instance (#611)

- Add setup_forge() to bin/disinto: provisions Forgejo via Docker,
  creates admin + bot users (dev-bot, review-bot), generates API
  tokens, creates repo, and pushes code — all automated
- Rename env vars: CODEBERG_TOKEN→FORGE_TOKEN, REVIEW_BOT_TOKEN→
  FORGE_REVIEW_TOKEN, CODEBERG_REPO→FORGE_REPO, CODEBERG_API→
  FORGE_API, CODEBERG_WEB→FORGE_WEB, CODEBERG_BOT_USERNAMES→
  FORGE_BOT_USERNAMES (with backwards-compat fallbacks)
- Rename API helpers: codeberg_api()→forge_api(), codeberg_api_all()
  →forge_api_all() (with compat aliases)
- Add forge_url field to project TOML; load-project.sh derives
  FORGE_API/FORGE_WEB from forge_url + repo
- Update parse_repo_slug() to accept any host URL, not just codeberg
- Forgejo data stored under ~/.disinto/forgejo/ (not in factory repo)
- Update all 58 files: agent scripts, formulas, docs, site HTML

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

predictor/AGENTS.md

@@ -28,7 +28,7 @@ memory check (skips if available RAM < 2000 MB).
 
 **Key files**:
 - `predictor/predictor-run.sh` — Cron wrapper + orchestrator: lock, memory guard,
-  sources disinto project config, builds prompt with formula + Codeberg API
+  sources disinto project config, builds prompt with formula + forge API
   reference, creates tmux session (sonnet), monitors phase file, handles crash
   recovery via `run_formula_and_monitor`
 - `formulas/run-predictor.toml` — Execution spec: two steps (preflight,
@@ -37,7 +37,7 @@ memory check (skips if available RAM < 2000 MB).
   interactive session
 
 **Environment variables consumed**:
-- `CODEBERG_TOKEN`, `CODEBERG_REPO`, `CODEBERG_API`, `PROJECT_NAME`, `PROJECT_REPO_ROOT`
+- `FORGE_TOKEN`, `FORGE_REPO`, `FORGE_API`, `PROJECT_NAME`, `PROJECT_REPO_ROOT`
 - `PRIMARY_BRANCH`, `CLAUDE_MODEL` (set to sonnet by predictor-run.sh)
 - `MATRIX_TOKEN`, `MATRIX_ROOM_ID`, `MATRIX_HOMESERVER` — Notifications (optional)