revert: restore production to the state before 730d0bd (PM/RBAC work moved to 'pm')

Their three commits (730d0bd, 5a9b543, 387edfb) reached production by push and
auto-deployed. 387edfb expects a users.username column that the live database does
not have, so POST /api/v1/auth/login was returning HTTP 500. Their schema changes
never applied either (projects still has only id, name, description, start_date,
pm_user_id, created_at), so nothing depends on the reverted code.

This commit sets the tree back to exactly a02b3ea — verified with git diff against
it — while keeping history linear: the work itself is preserved on 'pm' at 387edfb.

sql/migration.sql

@@ -625,15 +625,4 @@ CREATE TABLE IF NOT EXISTS audit_log (
     details     JSONB       NOT NULL DEFAULT '{}'
 );
 
--- ---------- UNIFIED PROJECTS (PM & PROCUREMENT SHARED SCHEMA) ----------
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS location TEXT DEFAULT '';
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS project_manager TEXT DEFAULT '';
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS planned_start DATE;
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS planned_end DATE;
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS actual_start DATE;
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS actual_end DATE;
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS status TEXT DEFAULT 'ACTIVE';
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS progress DOUBLE PRECISION DEFAULT 0.0;
-ALTER TABLE projects ADD COLUMN IF NOT EXISTS updated_at TIMESTAMPTZ DEFAULT now();
-
 COMMIT;