docs: fix Phase-N references stale after MCP renumber

Sweep four call-sites pointing at the wrong phase number:

- README.md:19 — Norris mode "Phase 2" → Phase 3 (renumbered by 013c625)
- README.md:62 — safety.lua "Phase 2+" → Phase 3+ (same renumber)
- PHASE0.md:58 — safety.lua "(Phase 1)" → (Phase 3) (was wrong pre-013c625
  too — referenced Phase 1 when Norris was actually Phase 2)
- PHASE0.md:214 — Norris-mode prompt example "(Phase 1)" → (Phase 3)
  (same pre-existing wrong reference)

Caught by review of 013c625. No semantic change; mechanical phase-number
sweep only.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/PHASE0.md

@@ -55,7 +55,7 @@ aish/
 ├── executor.lua          # Command execution; Phase 0: io.popen
 ├── context.lua           # In-memory conversation history, token budget
 ├── history.lua           # Persistent session log + memory.jsonl (Phase 1)
-├── safety.lua            # Destructive op heuristic, Chuck Norris gate (Phase 1)
+├── safety.lua            # Destructive op heuristic, Chuck Norris gate (Phase 3)
 ├── renderer.lua          # Output formatting, ANSI sequences
 ├── config.lua            # Model registry, routing rules, user preferences
 └── ffi/
@@ -211,7 +211,7 @@ Prompt format:
 [aish:fast]>
 ```
 
-Where `fast` is the active model name as defined in `config.lua`. In Norris mode (Phase 1) this becomes:
+Where `fast` is the active model name as defined in `config.lua`. In Norris mode (Phase 3) this becomes:
 
 ```
 [aish:fast ⚡]>