feat: add run deletion, session reopen, and feed merging (v0.6.0)

- DELETE /api/sessions/{id}/runs/{run_id} removes stopped runs
- POST /api/sessions/{id}/reopen transitions Completed → Active
- Optional merge_feeds field on POST /api/sessions/{id}/runs combines
  frames from multiple feeds with priority-based deduplication
- In-place merge_frames() avoids 2× peak memory
- All new fields use #[serde(default)] for backward compatibility
- Updated README.md with new endpoints and feed merging docs

README.md

@@ -100,7 +100,7 @@ The terminal UI shows one panel per active feed:
 
 ```
 ┌──────────────────────────────────────────────────────────┐
-│           rusty-telemetry v0.5.0 -- Telemetry Listener   │
+│           rusty-telemetry v0.6.0 -- Telemetry Listener   │
 ├──────────────────────────────────────────────────────────┤
 │ ╔ * Receiving      ╗                                     │
 │ ║   20.0 Hz   1200 packets   15.2 KB/s   last: 0.05s    ║
@@ -151,9 +151,32 @@ Use-case sessions allow targeted data capture and analysis:
 2. **Start runs** — each run captures frames from the ring buffer between start and stop
 3. **Complete the session** — auto-analyzes captured data and stores results
 4. **Retrieve analysis** — shift point RPM ranges or track boundary coordinates
+5. **Re-open if needed** — re-open a completed session to add more runs, then complete again
+6. **Delete runs** — remove unwanted runs from a session (must be stopped first)
 
 Sessions are in-memory and independent of persistent recordings.
 
+#### Feed Merging
+
+When multiple feeds are available during a recording (e.g., both KSUDP on port 9996 and Telemetry Tool on port 10101), runs can merge frames from multiple sources for more accurate analysis data.
+
+To start a merged run, specify `merge_feeds` in the start run request:
+
+```json
+{
+  "feed_name": "ksudp",
+  "merge_feeds": ["telemetry_tool"]
+}
+```
+
+The merge algorithm:
+1. Extracts frames independently from each feed using ring buffer markers
+2. Sorts all frames by `(lap_count, lap_time_ms)`
+3. Deduplicates near-simultaneous frames (within 15ms) by keeping the higher-priority feed
+4. Feed priority: Telemetry Tool > KSUDP > PCARS
+
+This results in higher effective data density (combining 60 Hz TT + 20 Hz KSUDP) while preferring the richer Telemetry Tool data where available.
+
 ## REST API
 
 A built-in HTTP API server runs on port 8080 for recording management and live telemetry access.
@@ -178,6 +201,8 @@ A built-in HTTP API server runs on port 8080 for recording management and live t
 | DELETE | `/api/sessions/{id}` | Delete session |
 | POST | `/api/sessions/{id}/runs` | Start a run |
 | POST | `/api/sessions/{id}/runs/{run_id}/stop` | Stop a run |
+| DELETE | `/api/sessions/{id}/runs/{run_id}` | Delete a stopped run from session |
+| POST | `/api/sessions/{id}/reopen` | Re-open a completed session |
 | POST | `/api/sessions/{id}/complete` | Complete session + auto-analyze |
 | GET | `/api/sessions/{id}/analysis` | Get analysis results |
 | POST | `/api/sessions/{id}/analyze` | Re-run analysis on completed session |
@@ -236,10 +261,29 @@ All fields are optional.
 ```json
 {
   "feed_name": "ksudp",
-  "label": "Acceleration runs"
+  "label": "Acceleration runs",
+  "merge_feeds": ["telemetry_tool"]
 }
 ```
 
+`merge_feeds` is optional. When specified, frames from the listed feeds are merged with the primary feed's frames into a single deduplicated dataset. This is useful for combining the higher-frequency Telemetry Tool data (~60 Hz) with KSUDP data (~20 Hz) for more accurate analysis.
+
+### Delete Run
+
+Deletes a stopped run from a session. If the session was completed and had analysis results, the analysis is cleared (since the underlying data changed). Re-run analysis after deletion if needed.
+
+Returns `204 No Content` on success. Cannot delete a run that is currently recording — stop it first.
+
+### Reopen Session
+
+Re-opens a completed session, changing its status back to active. This clears the `completed_at` timestamp and any analysis results, allowing new runs to be added. Complete the session again when done to re-run analysis.
+
+```json
+{}
+```
+
+Returns the updated session on success.
+
 ### Use Cases Response
 
 ```json