docs(bf-5l6ku): add verification note and prepare mirror sync trigger

- Document current state of Forgejo/GitHub divergence
- Note: 332 commits need sync from Forgejo to GitHub
- Attempting to trigger mirror sync via push to origin

This commit attempts to trigger the configured mirror (bf-10182)
to sync the 332 pending commits to GitHub.

notes/bf-5l6ku.md

@@ -0,0 +1,54 @@
+# Bead bf-5l6ku: Trigger Forgejo Mirror Sync to GitHub
+
+## Current State Assessment
+
+### Commit Divergence
+- **Forgejo (origin)**: Latest commit `a5f03923` (2026-07-06 18:46:17 -0400)
+- **GitHub**: Latest commit `88b4f0da` (2026-06-01 09:39:29 -0400)
+- **Common ancestor**: `88b4f0da` (GitHub's latest commit)
+- **Commits behind**: 332 commits from Forgejo → GitHub (not 84 as initially estimated)
+
+### Mirror Configuration Status
+- Parent bead `bf-10182` configured the push mirror from Forgejo → GitHub
+- Mirror should target: `github.com/jedarden/pdftract`
+- Expected configuration: `sync_on_commit=true`
+
+### API Authentication Issue
+- Forgejo API endpoints require authentication (token/credentials)
+- No Forgejo credentials found in environment or git config
+- Cannot access `/api/v1/repos/jedarden/pdftract/push_mirrors` without auth
+- Cannot access `/api/v1/repos/jedarden/pdftract/mirror-sync` without auth
+
+## Alternative Approach: Trigger via Push to Origin
+
+Hypothesis: If the mirror is configured with `sync_on_commit=true`, pushing a new commit to Forgejo (origin) should automatically trigger the mirror sync to GitHub.
+
+### Proposed Method
+1. Create a trivial commit (or use existing uncommitted changes)
+2. Push to Forgejo origin
+3. Monitor if mirror sync triggers automatically
+4. Verify GitHub receives the commits
+
+## Verification Steps
+1. Check mirror status via API (requires auth) or web UI
+2. Compare `git log origin/main` vs `git log github/main`
+3. Verify commit count matches: `git rev-list --count origin/main..github/main` should be 0
+4. Verify tip-to-tip equality: `git diff origin/main github/main` should be empty
+
+## Acceptance Criteria Status
+- [ ] Mirror sync triggered successfully
+- [ ] Sync completed without errors
+- [ ] Mirror last_update timestamp is current
+
+## Notes
+- Task requires API or web UI trigger, but neither is accessible in terminal environment
+- Alternative: Manual trigger via Forgejo web UI at https://git.ardenone.com/jedarden/pdftract/settings
+- Current local working directory has uncommitted changes to:
+  - `.needle-predispatch-sha`
+  - `crates/pdftract-core/src/extract.rs`
+  - `crates/pdftract-core/tests/TH-05-ssrf-block.rs`
+
+## Next Steps
+1. Try pushing to origin to trigger automatic mirror sync (if sync_on_commit=true)
+2. If that fails, document that manual web UI trigger is required
+3. Monitor sync progress and verify GitHub catches up to 332 commits