docs: Document deprecation timeline and add removal warnings (bd-pndo)

- Add Deprecated section to CHANGELOG.md listing all deprecated commands
- Set removal target: v1.0.0 for all deprecated commands
- Add '(will be removed in v1.0.0)' to all deprecation messages
- Add proper Deprecated field to admin_aliases.go (cleanup, compact, reset)
- Remove manual warning prints from admin aliases (Cobra handles it)

Deprecated commands documented:
- bd relate/unrelate → bd dep relate/unrelate
- bd daemons → bd daemon <subcommand>
- bd cleanup/compact/reset → bd admin <command>
- bd comment → bd comments add
- bd template* → bd mol/formula commands
- bd detect-pollution → bd doctor --check=pollution
- bd migrate-* → bd migrate <subcommand>

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/migrate_sync.go

@@ -65,7 +65,7 @@ func init() {
 	migrateSyncAliasCmd := *migrateSyncCmd
 	migrateSyncAliasCmd.Use = "migrate-sync"
 	migrateSyncAliasCmd.Hidden = true
-	migrateSyncAliasCmd.Deprecated = "use 'bd migrate sync' instead"
+	migrateSyncAliasCmd.Deprecated = "use 'bd migrate sync' instead (will be removed in v1.0.0)"
 	rootCmd.AddCommand(&migrateSyncAliasCmd)
 }