[AAASM-4837] 📝 (examples): Correct node examples' fictional real-provider-mode guidance

[Chisanan232]

What changed

The six node/* example READMEs described a "real-provider mode" that does
not exist. Several claimed that copying .env.example to .env and setting
AAASM_GATEWAY_URL / OPENAI_API_KEY would make pnpm start "connect to the
real gateway and real OpenAI API," and two shipped an impossible
Gateway connection refused → omit AAASM_GATEWAY_URL troubleshooting row. In
reality none of the node/*/src files read any environment variable,
dotenv, or initAssembly (grep → 0 matches): the offline, in-process
fail-closed policy stub (createPolicyGatewayClient in each src/policy.ts)
always runs, so those env vars have zero effect. node/custom-tool-policy also
referenced a .env.example that never existed in its directory.

This PR corrects the docs to match reality (honest-minimal — no code wiring):

• Replaced every "Real-provider mode" / "Note on .env.example" section with a
  single consistent "Offline-only demo (no real-provider mode)" note that
  states the example runs fully offline via the local policy stub, reads no env
  vars, and that real gateway/LLM wiring is a possible future enhancement, not
  current behavior.
• Removed the two impossible "Gateway connection refused" troubleshooting rows.
• Deleted the five non-functional .env.example files (their vars are never
  read) and removed all references to them, including the dangling reference in
  custom-tool-policy.

No node/*/src/*.ts was touched. In particular openai-node-tool-policy/src/tools.ts
is deliberately left to sibling ticket AAASM-4846.

Follow-up (out of scope here): actually wiring real initAssembly env-driven
behavior into these six examples would be a separate feature ticket, not a doc fix.

Related ticket

Closes AAASM-4837
Jira: https://lightning-dust-mite.atlassian.net/browse/AAASM-4837

How to verify

• grep -rn "process.env\|dotenv\|initAssembly" node/*/src/ → still 0 matches
  (the env vars genuinely have no effect).
• grep -rn "Real-provider\|cp .env\|connect to the real\|Gateway connection refused" node/*/README.md
  → no matches (fiction removed).
• ls node/*/.env.example → none remain; no README references .env.example.
• Each README's remaining AAASM_GATEWAY_URL/OPENAI_API_KEY mention is only
  inside the honest "these have no effect here" note.

Checklist

• PR title follows [AAASM-XXXX] <GitEmoji> (<scope>): <summary>
• No secrets, API keys, or .env files committed
• Example sub-projects include their own README.md with prerequisites and run instructions
• SDK/runtime version dependencies are documented or pinned

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Chisanan232]

🤖 Claude Code — PR review

Scope (AAASM-4837, MED): ✅ 6 node READMEs corrected to honest offline-only; 5 non-functional .env.example removed; no false 'real-provider mode'.

1. CI ✅ green. 2. Scope ✅ READMEs + deletions, no src touched. 3. Side effects none. 4. FE n/a. Verdict: ready to merge pending Pioneer approval.