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>

tools/orchestrator/continue-prompt.sh

@@ -30,6 +30,8 @@ done
 
 _require_jq
 require_mission "$PROJECT"
+target_runtime="$(coord_runtime)"
+launch_cmd="$(coord_launch_command)"
 
 # ─── Load mission data ──────────────────────────────────────────────────────
 
@@ -93,6 +95,22 @@ if (( session_count > 0 )); then
   fi
 fi
 
+# Write machine-readable next-task capsule for deterministic runtime launches.
+write_next_task_capsule \
+  "$PROJECT" \
+  "$target_runtime" \
+  "$mission_id" \
+  "$mission_name" \
+  "$project_path" \
+  "$quality_gates" \
+  "$current_ms_id" \
+  "$current_ms_name" \
+  "$next_task" \
+  "$tasks_done" \
+  "$tasks_total" \
+  "$pct" \
+  "$current_branch"
+
 # ─── Generate prompt ────────────────────────────────────────────────────────
 
 prompt="$(cat <<EOF
@@ -108,6 +126,7 @@ Continue **$mission_name** from existing state.
 - **Scratchpad:** docs/scratchpads/${mission_id}.md
 - **Protocol:** ~/.config/mosaic/guides/ORCHESTRATOR.md
 - **Quality gates:** $quality_gates
+- **Target runtime:** $target_runtime
 
 ## Resume Point
 
@@ -129,9 +148,10 @@ Continue **$mission_name** from existing state.
 3. Read \`docs/scratchpads/${mission_id}.md\` for session history and decisions
 4. Read \`docs/TASKS.md\` for current task state
 5. \`git pull --rebase\` to sync latest changes
-6. Continue execution from task **${next_task:-next-pending}**
-7. Follow Two-Phase Completion Protocol
-8. You are the SOLE writer of \`docs/TASKS.md\`
+6. Launch runtime with \`$launch_cmd\`
+7. Continue execution from task **${next_task:-next-pending}**
+8. Follow Two-Phase Completion Protocol
+9. You are the SOLE writer of \`docs/TASKS.md\`
 EOF
 )"