feat(CF-524): Add project_archive MCP method

Implements complete project archival workflow:
- Migration 024: Add archival fields to projects table
- New project-archive.ts tool coordinating:
  * Tarball creation via shell
  * S3 upload with vault credentials
  * Database metadata tracking
  * Optional local deletion
  * Cleanup of temp files
- Registered in tool definitions and handlers

Replaces manual archival process used for Fireberries/CyprusPulse.

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

migrations/024_add_project_archival_fields.sql

@@ -0,0 +1,20 @@
+-- Migration 024: Add project archival tracking fields
+-- Adds fields to track S3 archival of complete projects
+
+ALTER TABLE projects
+    ADD COLUMN IF NOT EXISTS archived_at TIMESTAMP WITH TIME ZONE,
+    ADD COLUMN IF NOT EXISTS archive_location TEXT,
+    ADD COLUMN IF NOT EXISTS archive_size BIGINT,
+    ADD COLUMN IF NOT EXISTS archived_by_session TEXT;
+
+CREATE INDEX IF NOT EXISTS idx_projects_archived ON projects(archived_at) WHERE archived_at IS NOT NULL;
+
+COMMENT ON COLUMN projects.archived_at IS 'Timestamp when project was archived to S3';
+COMMENT ON COLUMN projects.archive_location IS 'S3 path to archived tarball (e.g., s3://agiliton-archive/projects/Project-20260127.tar.gz)';
+COMMENT ON COLUMN projects.archive_size IS 'Size of archive in bytes';
+COMMENT ON COLUMN projects.archived_by_session IS 'Session ID that performed the archival';
+
+-- Record migration
+INSERT INTO schema_migrations (version, applied_at)
+VALUES ('024_add_project_archival_fields', NOW())
+ON CONFLICT DO NOTHING;