Refactor packages/astro/src/server/keyless/utils.ts to use the shared
resolveKeysWithKeylessFallback utility from @clerk/shared/keyless,
matching the pattern used by React Router and TanStack Start.

This removes ~70 lines of duplicated code and ensures consistent
behavior across all frameworks.

Changes:
- Import sharedResolveKeysWithKeylessFallback from @clerk/shared/keyless
- Re-export KeylessResult type from shared package
- Simplify wrapper to create keylessService and call shared utility
- Remove duplicated logic (claimed keys flow, cache management, etc.)

Benefits:
✅ Keeps codebase DRY
✅ Ensures consistent behavior across frameworks
✅ Makes maintenance easier (single source of truth)
✅ Reduces test surface area

Aligns Astro's keyless implementation with React Router/TanStack Start patterns
for consistency and maintainability.

Changes:

1. file-storage.ts:
   - Use static imports without .default destructuring
   - Pass entire module namespace to createNodeFileStorage
   - Add error handling with helpful message
   - Match React Router's implementation pattern

2. keyless/index.ts:
   - Accept context and options parameters (like React Router)
   - Add canUseFileSystem() runtime check
   - Add init promise to prevent race conditions
   - Add resetKeylessService() for testing
   - Use createClerkClient directly instead of inline creation
   - Add proper error handling and logging

3. keyless/utils.ts:
   - Pass context and options to keyless service
   - Update function signature to match new pattern

4. feature-flags.ts:
   - Use getEnvVariable helper instead of direct process.env
   - Remove hasFileSystemSupport() (handled by keyless service)
   - Simplify to match React Router's cleaner pattern

5. get-safe-env.ts:
   - Remove 'as any' type cast (line 59)
   - Use proper App.Locals type from env.d.ts
   - Improve type safety throughout

6. clerk-middleware.ts:
   - Export ClerkAstroMiddlewareOptions type
   - Pass context and options to resolveKeysWithKeylessFallback

Benefits:
✅ Consistent patterns across React Router/TanStack Start/Astro
✅ Better type safety (no 'any' casts)
✅ Cleaner separation of concerns
✅ Race condition protection with init promise
✅ Better error handling and logging
✅ More testable with resetKeylessService()
✅ Follows shared utility patterns (DRY)

Replace manual createClerkClient calls with the existing clerkClient helper,
matching React Router's pattern of reusing the framework's client factory.

Changes:
- Import clerkClient from '../clerk-client' instead of createClerkClient from @clerk/backend
- Use clerkClient(context) in createAccountlessApplication and completeOnboarding
- Remove manual client configuration (secretKey, publishableKey, apiUrl, userAgent)
- Client now properly inherits all configuration from getSafeEnv(context)

Benefits:
✅ DRY - reuses existing client configuration logic
✅ Consistent - all API calls use same client setup
✅ Maintainable - client config changes apply everywhere
✅ Matches React Router pattern exactly
✅ Inherits telemetry, sdkMetadata, and all other configs automatically

Fix unused parameters and ensure options are properly passed through the
call chain, matching React Router's pattern exactly.

Changes:

1. clerk-client.ts:
   - Update clerkClient signature to accept optional options parameter
   - Now matches React Router: clerkClient(context, options?)
   - Allows keyless service to override client configuration

2. keyless/index.ts:
   - Pass options parameter to clerkClient() calls
   - Options now used in createAccountlessApplication
   - Options now used in completeOnboarding
   - Fixes unused parameter warning

3. clerk-middleware.ts:
   - Remove unused 'error' variable in catch block
   - Use empty catch block (matches React Router pattern)

4. keyless/utils.ts:
   - Fix import sorting (ESLint auto-fix)

Benefits:
✅ No unused parameters
✅ Options properly passed through call chain
✅ clerkClient can be overridden with custom config
✅ Matches React Router pattern exactly
✅ All ESLint errors resolved
✅ All TypeScript type checks pass

The options parameter in clerkClient was not providing any value because
getSafeEnv(context) already reads all necessary configuration from both
process.env and context.locals (which includes keyless values set by middleware).

Changes:

1. clerk-client.ts:
   - Remove optional options parameter from clerkClient signature
   - Keep createClerkClientWithOptions internal signature for potential future use
   - Client configuration fully driven by getSafeEnv(context)

2. keyless/index.ts:
   - Remove ClerkAstroMiddlewareOptions import (no longer needed)
   - Remove options parameter from keyless() function
   - Remove options from clerkClient() calls
   - Simplify function signature

3. keyless/utils.ts:
   - Remove ClerkAstroMiddlewareOptions import
   - Remove options parameter from resolveKeysWithKeylessFallback()
   - Update keyless() call to not pass options

4. clerk-middleware.ts:
   - Remove options parameter from resolveKeysWithKeylessFallback() call

Why this is correct:
- getSafeEnv(context) reads from process.env via getContextEnvVar()
- getSafeEnv(context) reads keyless values from context.locals
- All necessary config (keys, urls, telemetry) is already available
- The spread ...options at end of createClerkClient was never overriding anything useful
- Simplifies the API and removes unnecessary parameters

Benefits:
✅ Simpler API surface
✅ No unused parameters
✅ Clear single source of truth (getSafeEnv)
✅ Less confusing for developers
✅ All type checks pass