feat: Production readiness improvements for WHOOSH council formation

Major security, observability, and configuration improvements:

## Security Hardening
- Implemented configurable CORS (no more wildcards)
- Added comprehensive auth middleware for admin endpoints
- Enhanced webhook HMAC validation
- Added input validation and rate limiting
- Security headers and CSP policies

## Configuration Management
- Made N8N webhook URL configurable (WHOOSH_N8N_BASE_URL)
- Replaced all hardcoded endpoints with environment variables
- Added feature flags for LLM vs heuristic composition
- Gitea fetch hardening with EAGER_FILTER and FULL_RESCAN options

## API Completeness
- Implemented GetCouncilComposition function
- Added GET /api/v1/councils/{id} endpoint
- Council artifacts API (POST/GET /api/v1/councils/{id}/artifacts)
- /admin/health/details endpoint with component status
- Database lookup for repository URLs (no hardcoded fallbacks)

## Observability & Performance
- Added OpenTelemetry distributed tracing with goal/pulse correlation
- Performance optimization database indexes
- Comprehensive health monitoring
- Enhanced logging and error handling

## Infrastructure
- Production-ready P2P discovery (replaces mock implementation)
- Removed unused Redis configuration
- Enhanced Docker Swarm integration
- Added migration files for performance indexes

## Code Quality
- Comprehensive input validation
- Graceful error handling and failsafe fallbacks
- Backwards compatibility maintained
- Following security best practices

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

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

vendor/github.com/golang-migrate/migrate/v4/database/postgres/README.md

@@ -0,0 +1,39 @@
+# postgres
+
+`postgres://user:password@host:port/dbname?query` (`postgresql://` works, too)
+
+| URL Query  | WithInstance Config | Description |
+|------------|---------------------|-------------|
+| `x-migrations-table` | `MigrationsTable` | Name of the migrations table |
+| `x-migrations-table-quoted` | `MigrationsTableQuoted` | By default, migrate quotes the migration table for SQL injection safety reasons. This option disable quoting and naively checks that you have quoted the migration table name. e.g. `"my_schema"."schema_migrations"` |
+| `x-statement-timeout` | `StatementTimeout` | Abort any statement that takes more than the specified number of milliseconds |
+| `x-multi-statement` | `MultiStatementEnabled` | Enable multi-statement execution (default: false) |
+| `x-multi-statement-max-size` | `MultiStatementMaxSize` | Maximum size of single statement in bytes (default: 10MB) |
+| `dbname` | `DatabaseName` | The name of the database to connect to |
+| `search_path` | | This variable specifies the order in which schemas are searched when an object is referenced by a simple name with no schema specified. |
+| `user` | | The user to sign in as |
+| `password` | | The user's password | 
+| `host` | | The host to connect to. Values that start with / are for unix domain sockets. (default is localhost) |
+| `port` | | The port to bind to. (default is 5432) |
+| `fallback_application_name` | | An application_name to fall back to if one isn't provided. |
+| `connect_timeout` | | Maximum wait for connection, in seconds. Zero or not specified means wait indefinitely. |
+| `sslcert` | | Cert file location. The file must contain PEM encoded data. |
+| `sslkey` | | Key file location. The file must contain PEM encoded data. |
+| `sslrootcert` | | The location of the root certificate file. The file must contain PEM encoded data. | 
+| `sslmode` | | Whether or not to use SSL (disable\|require\|verify-ca\|verify-full) |
+
+
+## Upgrading from v1
+
+1. Write down the current migration version from schema_migrations
+1. `DROP TABLE schema_migrations`
+2. Wrap your existing migrations in transactions ([BEGIN/COMMIT](https://www.postgresql.org/docs/current/static/transaction-iso.html)) if you use multiple statements within one migration.
+3. Download and install the latest migrate version.
+4. Force the current migration version with `migrate force <current_version>`.
+
+## Multi-statement mode
+
+In PostgreSQL running multiple SQL statements in one `Exec` executes them inside a transaction. Sometimes this
+behavior is not desirable because some statements can be only run outside of transaction (e.g.
+`CREATE INDEX CONCURRENTLY`). If you want to use `CREATE INDEX CONCURRENTLY` without activating multi-statement mode
+you have to put such statements in a separate migration files.