Add MCP health check and profile lookup helpers

[anhtahaylove]

Summary

• add health_check for ShardX Launcher API reachability/auth checks
• add find_profile_by_name to locate profiles by id/name without returning full fingerprint config
• add ensure_profile_started to idempotently resolve/start a profile and return its CDP endpoint
• add safe_open_url to resolve/start a profile, open an http(s) URL, and return title/url for MCP smoke checks
• let the MCP server read SHARDX_API / SHARDX_TOKEN from Windows user environment when stdio clients strip custom env vars
• document the Codex/Cursor-friendly setup and helper flow

Why

These helpers make MCP clients safer to bootstrap and automate against ShardX Launcher:

• clients can detect whether the launcher is reachable and whether SHARDX_TOKEN is valid before mutating calls
• clients can resolve human-friendly profile names without inspecting full profile objects
• agents can do a one-shot profile-start + page-open smoke test without manually chaining low-level tools
• Windows stdio clients that whitelist inherited env vars can still use the user-level token without copying secrets into client config

This PR intentionally does not change browser engine behavior, fingerprint behavior, profile isolation, or the launcher API contract.

Test

• node --check mcp/index.js
• local MCP smoke test against ShardX Launcher v0.1.10:
  • health_check authenticated with token from Windows user env fallback
  • find_profile_by_name found VN Automation 001 - No Proxy
  • ensure_profile_started returned an existing CDP endpoint
  • safe_open_url opened https://example.com/ and returned Example Domain
  • safe_open_url rejected file://... with safe_open_url only supports http(s) URLs

[anhtahaylove]

Tidied my open PRs here against current main so the queue reflects reality — 7 closed, 3 left, all rebased and mergeable.

Closed as superseded (each with the specific reason on the PR):

• Improve launcher profile launch error states #20, Improve Automation API token settings UX #21, feat(ui): add proxy during profile creation #28 — touched src/App.tsx / src/App.css, which 0d0108b (v2 update) deleted in favour of the feature-sliced layout. Nothing left to rebase onto.
• Support name tags in proxy bulk import #25 — main already parses the #name tag (proxy.rs:283), and keeps country=/note= readable for older exports, which is better than what I had.
• Allow canvas noise overrides for temporary profiles #26 — main already applies per-vector noise overrides on temporary profiles (api.rs:287-291) via a shared apply_noise_overrides helper.
• Improve MCP setup guidance in Settings #22 — upstream downloads the MCP bundle from R2 instead of probing the filesystem, so my find_existing_mcp helpers have no role.
• Sync v0.2.x: encrypted profile backup, v2 control plane, and fleet sync #37 — a fork-sync of 33 commits that has structurally diverged; not landable as one PR.

Still open, rebased onto current main, no conflicts:

PR	What it adds	Size
#19	health_check (fail fast when the launcher is closed or the token is stale) and find_profile_by_name MCP tools	185+/6−
#23	devtools_context MCP tool + Tauri command returning the CDP endpoint and per-target DevTools URL, for handing a live profile to a human	219+/1−
#24	encoding="utf-8" on the Python SDK's file IO — without it a profile name with non-ASCII characters is written mojibake or throws UnicodeDecodeError on Windows	8+/8−

Verification on my side: node --check on mcp/index.js, cargo check clean for #23, and an AST sweep confirming zero remaining unencoded read_text/write_text calls for #24. I dropped some .pyc files and a generated windows-schema.json that had crept into earlier revisions.

No rush from my side — flagging only because all three are small and independent, so they can be taken in any order or declined individually. One unrelated note: sdks/python/shardx/__pycache__/*.pyc is tracked on main and .gitignore has no __pycache__ rule.