docs: Update docs to reflect molecule-first paradigm (gt-nam3)

- Add molecule-first paradigm note at top of architecture.md
- Update all spawn examples to include --molecule flag
- Add "Config vs Molecule" section with cognition principle
- Add policy-to-molecule escalation note in federation-design.md
- Update role templates (mayor, witness) with molecule usage

Key message: Gas Town spawns workers on molecules, not just issues.
The issue is seed data; the molecule defines the workflow.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/federation-design.md

@@ -394,6 +394,8 @@ policy:
       prefer: gce-worker-1
 ```
 
+**When policy becomes a molecule**: Static policy handles simple preference-based routing. But when assignment requires cognition - analyzing work characteristics, checking outpost health in real-time, making cost/speed tradeoffs, or handling degraded outposts - escalate to `mol-outpost-assign`. The policy file declares preferences; the molecule executes intelligent assignment. See [Config vs Molecule](architecture.md#config-vs-molecule-when-to-use-which) for the general principle.
+
 ## Implementation Phases
 
 ### Phase 1: Outpost Abstraction (Local)