feat: API key gating for desktop cloud fallback + registration (#215)

* feat: API key gating for desktop cloud fallback + registration system

Gate desktop cloud fallback behind WORLDMONITOR_API_KEY — desktop users
need a valid key for cloud access, otherwise operate local-only (sidecar).
Add email registration system via Convex DB for future key distribution.

Client-side: installRuntimeFetchPatch() checks key presence before
allowing cloud fallback, with secretsReady promise + 2s timeout.
Server-side: origin-aware validation in sebuf gateway — desktop origins
require key, web origins pass through.

- Add WORLDMONITOR_API_KEY to 3-place secret system (Rust, TS, sidecar)
- New "World Monitor" settings tab with key input + registration form
- New api/_api-key.js server-side validation (origin-aware)
- New api/register-interest.js edge function with rate limiting
- Convex DB schema + mutation for email registration storage
- CORS headers updated for X-WorldMonitor-Key + Authorization
- E2E tests for key gate (blocked without key, allowed with key)
- Deployment docs (API_KEY_DEPLOYMENT.md) + updated desktop config docs

* fix: harden worldmonitor key + registration input handling

* fix: show invalid WorldMonitor API key status

* fix: simplify key validation, trim registration checks, add env example vars

- Inline getValidKeys() in _api-key.js
- Remove redundant type checks in register-interest.js
- Simplify WorldMonitorTab status to present/missing
- Add WORLDMONITOR_VALID_KEYS and CONVEX_URL to .env.example

* feat(sidecar): integrate proto gateway bundle into desktop build

The sidecar's buildRouteTable() only discovers .js files, so the proto
gateway at api/[domain]/v1/[rpc].ts was invisible — all 45 sebuf RPCs
returned 404 in the desktop app. Wire the existing build script into
Tauri's build commands and add esbuild as an explicit devDependency.

src-tauri/src/main.rs

@@ -25,7 +25,7 @@ const DESKTOP_LOG_FILE: &str = "desktop.log";
 const MENU_FILE_SETTINGS_ID: &str = "file.settings";
 const MENU_HELP_GITHUB_ID: &str = "help.github";
 const MENU_HELP_DEVTOOLS_ID: &str = "help.devtools";
-const SUPPORTED_SECRET_KEYS: [&str; 20] = [
+const SUPPORTED_SECRET_KEYS: [&str; 21] = [
     "GROQ_API_KEY",
     "OPENROUTER_API_KEY",
     "FRED_API_KEY",
@@ -46,6 +46,7 @@ const SUPPORTED_SECRET_KEYS: [&str; 20] = [
     "NASA_FIRMS_API_KEY",
     "OLLAMA_API_URL",
     "OLLAMA_MODEL",
+    "WORLDMONITOR_API_KEY",
 ];
 
 #[derive(Default)]