fix: make migrations 048/049 safe for environments without canonical tables

Migrations 048 and 049 reference canonical_processed_chunks and
canonical_controls tables which may not exist on all environments.
Wrap ALTER TABLE statements in DO blocks that check for table
existence first. This unblocks migrations 050-053 on production.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-compliance/migrations/048_processing_path_expand.sql

@@ -1,17 +1,22 @@
 -- 048: Expand processing_path CHECK constraint for new pipeline paths
 -- New values: prefilter_skip, no_control, store_failed, error
+-- Safe: only runs if the table exists (may not exist on all environments)
 
-ALTER TABLE canonical_processed_chunks
-    DROP CONSTRAINT IF EXISTS canonical_processed_chunks_processing_path_check;
-
-ALTER TABLE canonical_processed_chunks
-    ADD CONSTRAINT canonical_processed_chunks_processing_path_check
-    CHECK (processing_path IN (
-        'structured',       -- Rule 1/2: structured from original text
-        'llm_reform',       -- Rule 3: LLM reformulated
-        'skipped',          -- Legacy: skipped for other reasons
-        'prefilter_skip',   -- Local LLM determined chunk has no requirement
-        'no_control',       -- Processing ran but no control could be derived
-        'store_failed',     -- Control generated but DB store failed
-        'error'             -- Processing error occurred
-    ));
+DO $$
+BEGIN
+    IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'canonical_processed_chunks') THEN
+        ALTER TABLE canonical_processed_chunks
+            DROP CONSTRAINT IF EXISTS canonical_processed_chunks_processing_path_check;
+        ALTER TABLE canonical_processed_chunks
+            ADD CONSTRAINT canonical_processed_chunks_processing_path_check
+            CHECK (processing_path IN (
+                'structured',
+                'llm_reform',
+                'skipped',
+                'prefilter_skip',
+                'no_control',
+                'store_failed',
+                'error'
+            ));
+    END IF;
+END $$;

backend-compliance/migrations/049_target_audience.sql

@@ -1,8 +1,13 @@
 -- 049: Add target_audience field to canonical_controls
 -- Distinguishes who a control is relevant for: enterprises, authorities, providers, or all.
+-- Safe: only runs if the table exists (may not exist on all environments)
 
-ALTER TABLE canonical_controls ADD COLUMN IF NOT EXISTS
-    target_audience VARCHAR(20) DEFAULT NULL
-    CHECK (target_audience IN ('enterprise', 'authority', 'provider', 'all'));
-
-CREATE INDEX IF NOT EXISTS idx_cc_target_audience ON canonical_controls(target_audience);
+DO $$
+BEGIN
+    IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'canonical_controls') THEN
+        ALTER TABLE canonical_controls ADD COLUMN IF NOT EXISTS
+            target_audience VARCHAR(20) DEFAULT NULL
+            CHECK (target_audience IN ('enterprise', 'authority', 'provider', 'all'));
+        CREATE INDEX IF NOT EXISTS idx_cc_target_audience ON canonical_controls(target_audience);
+    END IF;
+END $$;