docs(04-02): complete CLI flag wiring plan summary and state updates

- 04-02-SUMMARY.md: --filter and --read flags wired, pcap mode, deriveOutputPath
- STATE.md: advanced to plan 2/2, updated decisions, session record
- ROADMAP.md: phase 4 marked Complete (2/2 plans)

.planning/STATE.md

@@ -2,14 +2,14 @@
 gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
-status: Ready to execute
-stopped_at: Completed 04-power-user-features 04-01-PLAN.md
-last_updated: "2026-03-26T13:35:55.000Z"
+status: Phase complete — ready for verification
+stopped_at: Completed 04-power-user-features 04-02-PLAN.md
+last_updated: "2026-03-26T13:42:19.484Z"
 progress:
   total_phases: 4
-  completed_phases: 3
+  completed_phases: 4
   total_plans: 11
-  completed_plans: 10
+  completed_plans: 11
 ---
 
 # Project State
@@ -56,6 +56,7 @@ Plan: 2 of 2
 | Phase 03-pipeline-integration-and-mvp P01 | 15min | 2 tasks | 6 files |
 | Phase 03 P02 | 5min | 1 tasks | 1 files |
 | Phase 04-power-user-features P01 | 3min | 2 tasks | 9 files |
+| Phase 04-power-user-features P02 | 4min | 1 tasks | 2 files |
 
 ## Accumulated Context
 
@@ -91,6 +92,9 @@ Recent decisions affecting current work:
 - [Phase 03-02]: Audio duration computed from snapshot count * DefaultWindowMs (not wall-clock) to avoid truncation for short captures
 - [Phase 04-power-user-features]: OpenCapture/StartCapture accept filter string; empty = no filter (backward compatible with live mode)
 - [Phase 04-power-user-features]: AggregatePcap: synchronous drain of events channel then assign to windows by Timestamp offset; gap windows pre-initialized with empty maps
+- [Phase 04-02]: bpfFilter and readPath are package-level globals for Cobra flag binding (same pattern as other flags)
+- [Phase 04-02]: runPcapMode checks for empty snapshots after PrintSummary so user sees zero-count table before error
+- [Phase 04-02]: deriveOutputPath uses filepath.Ext (last extension only) matching tcpdump convention
 
 ### Pending Todos
 
@@ -104,6 +108,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-26T13:35:54.993Z
-Stopped at: Completed 04-power-user-features 04-01-PLAN.md
+Last session: 2026-03-26T13:42:19.476Z
+Stopped at: Completed 04-power-user-features 04-02-PLAN.md
 Resume file: None