feat: add multi-runtime support (coord run, prdy --codex) and next-task capsule

- coord/prdy subcommands now accept --claude/--codex runtime flags
- New `mosaic coord run` generates continuation context and launches
  selected runtime, replacing manual copy/paste workflow
- Next-task capsule (.mosaic/orchestrator/next-task.json) provides
  machine-readable execution context for deterministic session launches
- Codex strict orchestrator profile added to runtime/codex/RUNTIME.md
- Orchestrator protocol updated with between-session run flow
- New smoke-test.sh for orchestration behavior verification

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

guides/ORCHESTRATOR-PROTOCOL.md

@@ -131,9 +131,9 @@ If context usage is high, produce a handoff message:
 4. Commit all state files
 5. The coordinator will generate a continuation prompt for the next session
 
-### Continuation Prompt Format
+### Continuation Prompt and Capsule Format
 
-The coordinator generates this (via `mosaic coord continue`):
+The coordinator generates this (via `mosaic coord continue`) and writes a machine-readable capsule at `.mosaic/orchestrator/next-task.json`:
 
 ```
 ## Continuation Mission
@@ -152,6 +152,16 @@ Continue **{mission}** from existing state.
 4. Human launches new session and pastes the prompt
 5. New agent reads manifest, scratchpad, TASKS.md and continues
 
+### Between Sessions (r0 assisted)
+
+Use `mosaic coord run` to remove copy/paste steps:
+
+1. Agent stops
+2. Human runs `mosaic coord run [--claude|--codex]`
+3. Coordinator regenerates continuation prompt + `next-task.json`
+4. Coordinator launches selected runtime with scoped kickoff context
+5. New session resumes from next task
+
 ---
 
 ## 7. Failure Taxonomy Quick Reference
@@ -194,6 +204,7 @@ In r0, the Coordinator is Jason + shell scripts. No daemon. No automation.
 | `mosaic coord mission` | Show mission progress dashboard |
 | `mosaic coord status` | Check if agent session is still running |
 | `mosaic coord continue` | Generate continuation prompt for next session |
+| `mosaic coord run [--claude|--codex]` | Generate continuation context and launch runtime |
 | `mosaic coord resume` | Crash recovery (detect dirty state, generate fix) |
 | `mosaic coord resume --clean-lock` | Clear stale session lock after review |
 
@@ -201,7 +212,7 @@ In r0, the Coordinator is Jason + shell scripts. No daemon. No automation.
 
 ```
 init → launch agent → [agent works] → agent stops →
-status → mission → continue → launch agent → repeat
+status → mission → run → repeat
 ```
 
 ---