Add command documentation and improve daemon UX

- Added human-readable uptime formatting (51m 59s vs 3119.4 seconds)
- Fixed daemon stop race condition with SIGKILL
- Added markdown docs for 19 commands: blocked, comments, compact, daemon,
  delete, dep, epic, export, import, label, list, quickstart, rename-prefix,
  renumber, reopen, repos, restore, stale, sync
- Closed: bd-159, bd-152, bd-168
- Deleted test issues: bd-144, bd-145

Amp-Thread-ID: https://ampcode.com/threads/T-9f7c3fed-62de-4bcd-a059-8c1b77cdb841
Co-authored-by: Amp <amp@ampcode.com>

commands/delete.md

@@ -0,0 +1,32 @@
+---
+description: Delete issues and clean up references
+argument-hint: [issue-ids...] [--force]
+---
+
+Delete one or more issues and clean up all references.
+
+## Safety Features
+
+- **Preview mode**: Default shows what would be deleted
+- **--force**: Required to actually delete
+- **--dry-run**: Preview collision detection
+- **Dependency checks**: Fails if issue has dependents (unless --cascade or --force)
+
+## Batch Deletion
+
+- Delete multiple: `bd delete bd-1 bd-2 bd-3 --force`
+- Delete from file: `bd delete --from-file deletions.txt --force`
+
+## Dependency Handling
+
+- **Default**: Fails if issue has dependents not in deletion set
+- **--cascade**: Recursively delete all dependent issues
+- **--force**: Delete and orphan dependents
+
+## What Gets Deleted
+
+1. All dependency links (any type, both directions)
+2. Text references updated to "[deleted:ID]" in connected issues
+3. Issue removed from database
+
+This operation cannot be undone. Use with caution!