feat: canonical custom field types, validation, and type-aware querying

- Unify field types across all layers: Text, Textarea, SelectOne, SelectMultiple, Date, DateTime, Number
- Add CustomFieldValidationConfig with type-specific Zod schemas
- Add validateCustomFieldValue() dispatching per-type validation
- Add validation_config (JSONB) and default_value columns to custom_fields
- Replace ad-hoc date/datetime/pattern checks with centralized validator
- Type-aware cf.* query operators: gt:, gte:, lt:, lte:, before:, after:, contains:
- Type-aware admin builder UI with inline option editor, min/max, date ranges, constraints
- Type-aware ticket detail rendering: Number inputs, Textarea, SelectMultiple checkbox groups
- Backward compatible: legacy type names mapped to canonical; old pattern field still checked
- Update seed data to canonical PascalCase types
- Migration 0018: add validation_config and default_value to custom_fields

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

drizzle/migrations/meta/_journal.json

@@ -127,6 +127,13 @@
       "when": 1781095552496,
       "tag": "0017_redundant_the_renegades",
       "breakpoints": true
+    },
+    {
+      "idx": 18,
+      "version": "7",
+      "when": 1781551130161,
+      "tag": "0018_dapper_jack_power",
+      "breakpoints": true
     }
   ]
 }