refactor(quota): secure managed provider credentials (#2160)

- add shared owner-only credential storage for OpenCode Go, Ollama Cloud, and Cursor
- validate credentials before atomic writes using 0700 directories and 0600 files
- replace provider-specific credential routes with an allowlisted lifecycle API
- stop automatically reading Ollama's legacy cookie file
- stop reading or modifying Cursor's database during regular quota requests
- add explicit one-time Cursor credential import without mutating Cursor storage
- persist refreshed Cursor credentials only in OpenChamber-managed storage
- add Ollama Cloud and Cursor credential controls to provider settings
- preserve OpenCode Go tracking through the shared credential flow
- add VS Code credential management and Cursor quota parity
- reject authentication redirects, enforce request timeouts, and fail on unparseable usage pages
- mask stored secrets in API responses and extend quota security coverage
- update quota provider documentation

packages/web/server/lib/quota/DOCUMENTATION.md

@@ -18,7 +18,7 @@ These provider IDs are currently dispatchable via `fetchQuotaForProvider(provide
 | --- | --- | --- | --- |
 | `claude` | Claude | `providers/claude.js` | `anthropic`, `claude` |
 | `codex` | Codex | `providers/codex.js` | `openai`, `codex`, `chatgpt` |
-| `cursor` | Cursor | `providers/cursor.js` | `CURSOR_TOKEN` / `CURSOR_ACCESS_TOKEN`, `CURSOR_REFRESH_TOKEN`, optional token files, or Cursor desktop SQLite DB |
+| `cursor` | Cursor | `providers/cursor.js` | Environment/token files, OpenChamber-managed credentials, or explicit one-time Cursor import |
 | `google` | Google | `providers/google/index.js` | `google`, `google.oauth`, Antigravity accounts file |
 | `github-copilot` | GitHub Copilot | `providers/copilot.js` | `github-copilot`, `copilot` |
 | `github-copilot-addon` | GitHub Copilot Add-on | `providers/copilot.js` | `github-copilot`, `copilot` |
@@ -29,7 +29,7 @@ These provider IDs are currently dispatchable via `fetchQuotaForProvider(provide
 | `zhipuai-coding-plan` | Zhipu AI Coding Plan | `providers/zhipuai-coding-plan.js` | `zhipuai-coding-plan`, `zhipuai`, `zhipu` |
 | `minimax-coding-plan` | MiniMax Coding Plan (minimax.io) | `providers/minimax-coding-plan.js` / `providers/minimax-shared.js` | `minimax-coding-plan` |
 | `minimax-cn-coding-plan` | MiniMax Coding Plan (minimaxi.com) | `providers/minimax-cn-coding-plan.js` / `providers/minimax-shared.js` | `minimax-cn-coding-plan` |
-| `ollama-cloud` | Ollama Cloud | `providers/ollama-cloud.js` | Cookie file at `~/.config/ollama-quota/cookie` (raw session cookie string) |
+| `ollama-cloud` | Ollama Cloud | `providers/ollama-cloud.js` | Manual cookie stored under `~/.config/openchamber/quota/` |
 | `wafer` | Wafer.ai | `providers/wafer.js` | `wafer`, `wafer-ai`, `wafer_ai`, `wafer.ai` |
 | `opencode-go` | OpenCode Go | `providers/opencode-go.js` | Manual workspace ID and auth cookie stored under `~/.config/openchamber/quota/` |
 
@@ -45,7 +45,7 @@ All providers should return results via shared helpers to preserve API shape:
 Provider modules must export `providerId`, `providerName`, `aliases`, `isConfigured(auth?)`, and `fetchQuota()`.
 `fetchQuota()` should return a quota result with `usage.windows` keyed by window name (for example `5h`, `7d`, `daily`) and optional provider-specific `usage.models` data.
 
-OpenCode Go credentials are explicitly supplied by the user through Settings. OpenChamber never scans browser cookie stores. The server validates the credential before an atomic `0600` write and never returns the cookie through its API.
+OpenCode Go, Ollama Cloud, and Cursor credentials are explicitly managed through Settings. The server validates credentials before atomic `0600` writes and never returns secrets through its API. OpenChamber never scans browser cookie stores or automatically reads Cursor storage; Cursor import is an explicit one-time user action and never modifies Cursor's database.
 
 ## Add a new provider (quick steps)
 1. Choose module shape based on complexity: