v0.5.0: Service discovery and FQN format refactoring

- Changed service FQN format: service:version@username (colon instead of @)
- Added service discovery: direct lookup, random selection, paginated queries
- Updated parseServiceFqn to handle optional username for discovery
- Removed UUID privacy layer (service_index table)
- Updated storage interface with discovery methods (discoverServices, getRandomService, getServiceByFqn)
- Removed deprecated methods (getServiceByUuid, queryService, listServicesForUsername, findServicesByName, touchUsername, batchCreateServices)
- Updated API routes: /services/:fqn with three modes (direct, random, paginated)
- Changed offer/answer/ICE routes to offer-specific: /services/:fqn/offers/:offerId/*
- Added extracted fields to services table (service_name, version, username) for efficient discovery
- Created migration 0007 to update schema and migrate existing data
- Added discovery indexes for performance

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

migrations/0007_simplify_schema.sql

@@ -0,0 +1,54 @@
+-- V0.4.1 Migration: Simplify schema and add service discovery
+-- Remove privacy layer (service_index) and add extracted fields for discovery
+
+-- Step 1: Drop service_index table (privacy layer removal)
+DROP TABLE IF EXISTS service_index;
+
+-- Step 2: Create new services table with extracted fields for discovery
+CREATE TABLE services_new (
+  id TEXT PRIMARY KEY,
+  service_fqn TEXT NOT NULL,
+  service_name TEXT NOT NULL,
+  version TEXT NOT NULL,
+  username TEXT NOT NULL,
+  created_at INTEGER NOT NULL,
+  expires_at INTEGER NOT NULL,
+  FOREIGN KEY (username) REFERENCES usernames(username) ON DELETE CASCADE,
+  UNIQUE(service_fqn)
+);
+
+-- Step 3: Migrate existing data (if any) - parse FQN to extract components
+-- Note: This migration assumes FQN format is already "service:version@username"
+-- If there's old data with different format, manual intervention may be needed
+INSERT INTO services_new (id, service_fqn, service_name, version, username, created_at, expires_at)
+SELECT
+  id,
+  service_fqn,
+  -- Extract service_name: everything before first ':'
+  substr(service_fqn, 1, instr(service_fqn, ':') - 1) as service_name,
+  -- Extract version: between ':' and '@'
+  substr(
+    service_fqn,
+    instr(service_fqn, ':') + 1,
+    instr(service_fqn, '@') - instr(service_fqn, ':') - 1
+  ) as version,
+  username,
+  created_at,
+  expires_at
+FROM services
+WHERE service_fqn LIKE '%:%@%'; -- Only migrate properly formatted FQNs
+
+-- Step 4: Drop old services table
+DROP TABLE services;
+
+-- Step 5: Rename new table to services
+ALTER TABLE services_new RENAME TO services;
+
+-- Step 6: Create indexes for efficient querying
+CREATE INDEX idx_services_fqn ON services(service_fqn);
+CREATE INDEX idx_services_discovery ON services(service_name, version);
+CREATE INDEX idx_services_username ON services(username);
+CREATE INDEX idx_services_expires ON services(expires_at);
+
+-- Step 7: Create index on offers for available offer filtering
+CREATE INDEX IF NOT EXISTS idx_offers_available ON offers(answerer_peer_id) WHERE answerer_peer_id IS NULL;