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/repos.md

@@ -0,0 +1,25 @@
+---
+description: Manage work across multiple repositories
+argument-hint: [command]
+---
+
+Manage work across multiple repositories when using a global daemon.
+
+**Requires**: Running global daemon (`bd daemon --global`)
+
+## Available Commands
+
+- **list**: List all cached repositories
+- **ready**: Show ready work across all repositories
+  - `--group`: Group results by repository
+- **stats**: Show combined statistics across all repositories
+- **clear-cache**: Clear all cached repository connections
+
+## Usage
+
+- `bd repos list` - See all repositories connected to global daemon
+- `bd repos ready` - View all ready work across projects
+- `bd repos ready --group` - Group ready work by repository
+- `bd repos stats` - Combined statistics from all repos
+
+Useful for managing multiple beads projects from a single global daemon.