feat(infra): tracing recovery, browser cleanup, CLI fixes, UI workspace split (#709)

- Tracing: recover stale running traces/spans on startup (PG + SQLite)
- Browser: Chrome orphan cleanup via launcher PID, timeouts, Leakless
- Claude CLI: WaitDelay 5s + context-cancel early exit
- Agent loop: safety-net defer to finalize orphan root traces
- UI: split workspace sharing into separate Memory and KG toggles
- Minor: for-range idiom, min() builtin

internal/agent/pruning.go

@@ -296,10 +296,7 @@ func estimateMessageChars(m providers.Message) int {
 // hasImportantTail checks if the last ~500 chars of content contain error/summary keywords.
 func hasImportantTail(content string) bool {
 	runes := []rune(content)
-	checkLen := 500
-	if checkLen > len(runes) {
-		checkLen = len(runes)
-	}
+	checkLen := min(500, len(runes))
 	tail := string(runes[len(runes)-checkLen:])
 	return importantTailRe.MatchString(tail)
 }