feat(tpmjs-spec): add auto-discovery of tools and rename exportName to name

Major changes to the TPMJS specification:

1. Auto-Discovery: The `tools` array is now optional. If omitted, TPMJS
   automatically scans package exports and registers any export with
   `description` and `execute` properties (standard AI SDK tool format).

2. Renamed `exportName` to `name` in tool definitions for cleaner spec.

3. Added `/list-exports` endpoint to Railway executor that:
   - Lists all exports from a package
   - Identifies valid AI SDK tools
   - Extracts descriptions for auto-discovered tools

4. Added `toolDiscoverySource` field to track 'auto' vs 'manual' discovery.

5. Updated tool page UI with:
   - Auto-discovery warning banner
   - Badge showing discovery source

6. Updated all documentation pages (docs, spec, publish) to reflect:
   - Optional tools array with auto-discovery
   - Use of `name` instead of `exportName`
   - Auto-extraction of schema and description

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/db/prisma/schema.prisma

@@ -75,6 +75,9 @@ model Tool {
   schemaSource      String?   @map("schema_source") @db.VarChar(20) // 'extracted' | 'author' | null
   schemaExtractedAt DateTime? @map("schema_extracted_at")
 
+  // Tool Discovery Fields
+  toolDiscoverySource String? @map("tool_discovery_source") @db.VarChar(20) // 'auto' | 'manual' | null
+
   // Tool Metrics
   qualityScore Decimal? @map("quality_score") @db.Decimal(3, 2) // 0.00 to 1.00