Logging overhaul: per-task log files, daemon.log drill-down

Switch from jobkit-daemon crate to jobkit with daemon feature.
Wire up per-task log files for all daemon-spawned agent tasks.

Changes:
- Use jobkit::daemon:: instead of jobkit_daemon::
- All agent tasks get .log_dir() set to $data_dir/logs/
- Task log path shown in daemon status and TUI
- New CLI: poc-memory agent daemon log --task NAME
  Finds the task's log path from status or daemon.log, tails the file
- LLM backend selection logged to daemon.log via log_event
- Targeted agent job names include the target key for debuggability
- Logging architecture documented in doc/logging.md

Two-level logging, no duplication:
- daemon.log: lifecycle events with task log path for drill-down
- per-task logs: full agent output via ctx.log_line()

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/main.rs

@@ -447,6 +447,9 @@ enum DaemonCmd {
     Log {
         /// Job name to filter by
         job: Option<String>,
+        /// Tail a task's log file (drill down from daemon log)
+        #[arg(long)]
+        task: Option<String>,
         /// Number of lines to show
         #[arg(long, default_value_t = 20)]
         lines: usize,
@@ -1043,7 +1046,13 @@ fn cmd_daemon(sub: DaemonCmd) -> Result<(), String> {
     match sub {
         DaemonCmd::Start => daemon::run_daemon(),
         DaemonCmd::Status => daemon::show_status(),
-        DaemonCmd::Log { job, lines } => daemon::show_log(job.as_deref(), lines),
+        DaemonCmd::Log { job, task, lines } => {
+            if let Some(ref task_name) = task {
+                daemon::show_task_log(task_name, lines)
+            } else {
+                daemon::show_log(job.as_deref(), lines)
+            }
+        }
         DaemonCmd::Install => daemon::install_service(),
         DaemonCmd::Consolidate => daemon::rpc_consolidate(),
         DaemonCmd::Run { agent, count } => daemon::rpc_run_agent(&agent, count),