docs(readme): add 13 free LLM providers and drop project claude settings

Adds LongCat, SenseNova, AMD Token Factory, Volcengine Ark, Baidu Qianfan,
iFlytek Spark, AIHubMix, OVHcloud AI Endpoints, LLM7.io, Token Harbor,
Aion Labs, Experiential Labs, and Empero to the free providers section,
each with limits, endpoint, source, and check date.

Removes .claude/settings.json; permissions now live in the ignored
settings.local.json.

plans/reports/research-260921-0932-additional-llm-providers.md

@@ -0,0 +1,54 @@
+# Research Report: Additional Budget/Free LLM Providers for README
+
+Date: 2026-09-21 09:32 (Asia/Saigon)
+
+## Executive Summary
+
+Goal: find free / budget LLM API providers and coding plans not yet in README.md. Two actively maintained
+curated lists (mnfst/awesome-free-llm-apis, pushed 2026-08-21; peter123023/awesome-free-llm-api, pushed
+2026-09-20, entries individually re-verified Aug 31–Sep 20) plus two official-doc fetches yielded **13 new
+free-tier providers**. No new request-based coding-plan subscription survived verification.
+
+Added to README (Free Providers): LongCat, SenseNova Token Plan, AMD Token Factory, Volcengine Ark,
+Baidu Qianfan, iFlytek Spark, AIHubMix, OVHcloud AI Endpoints, LLM7.io, Token Harbor, Aion Labs,
+Experiential Labs, Empero.
+
+## Methodology
+
+- Tool budget: 5 research calls (1 WebFetch 404, 2 WebSearch, 2 WebFetch). READMEs of 2 lists pulled via `gh api`.
+- Sources: 2 GitHub lists, LongCat official docs, AMD Radeon Cloud page (support page only, no pricing), ~12 search-result blogs (secondary, used only for candidate discovery).
+- Criteria: callable via API key + endpoint; free tier or ≤ ~$2/mo; source link available; not already in README.
+
+## Rejected candidates
+
+| Candidate | Reason |
+|---|---|
+| Chutes | No free endpoint since ~Sep 2026; all models priced (list re-checked 2026-09-12) |
+| B.AI | Free tier ended 2026-09-16 17:00 SGT |
+| Tencent Hunyuan | Old platform shuts 2026-09-30; new platform has no free models |
+| AtomCode CodingPlan Lite | Client-only 7-day trial, 500 claims/day, no public endpoint |
+| Together AI ($5), Nebius ($1), Novita ($0.50) | Trial-credit claims only from secondary blogs; no primary source within call budget |
+| Gemini CLI / Antigravity CLI, Qwen Code | CLI tools, not API providers; Qwen Code free OAuth ended 2026-04-15 |
+| Amazon Bedrock, Azure AI Foundry | Expiring cloud credits, no standing free tier |
+| DeepInfra | Charges from first token |
+
+## Flags on existing entries (not changed — out of scope)
+
+- **Mistral La Plateforme**: README says "~1B tokens/month". mnfst (Aug 2026) says Free plan = **$10/month API credits**, training opt-out needed, numeric rate limits no longer published. peter123023 (Sep 2026) marks the free API tier as **cancelled**. Needs re-verification against <https://mistral.ai/pricing>.
+- **TokenRouter**: Kimi K3 free promo expired 2026-08-12; current $0 models are qwen3.8-max-free, deepseek-v4-pro-0813-free, nemotron-3-nano-omni-free.
+- **OrcaRouter**: all dated offers (Aug 6/21/24) have passed.
+- **Kilo Code**: free pool now nvidia/nemotron-3-*, stepfun/step-3.7-flash, poolside/laguna-*, tencent/hy3 at 200 req/hr per IP, no key required.
+- **Cerebras**: mnfst lists gpt-oss-120b/20b, qwen3.6-27b at 30 RPM / 1,000 RPD.
+
+## References
+
+- <https://github.com/mnfst/awesome-free-llm-apis>
+- <https://github.com/peter123023/awesome-free-llm-api>
+- <https://longcat.chat/platform/docs/zh/>
+- <https://openrouter.ai/blog/tutorials/free-llm-apis-compared/>
+
+## Unresolved questions
+
+1. Mistral free tier: which of the three conflicting descriptions is current?
+2. LongCat exact daily quota — only visible in console after signup.
+3. AMD Token Factory: is `developer.amd.com.cn` reachable / usable outside mainland China?