fix: make migration 17 fully idempotent for databases in intermediate states (#481)

* fix: make migration 17 idempotent and standardize column names

Migration 17 renamed columns from sdk_session_id to memory_session_id,
but the migration wasn't fully idempotent - it could fail on databases
in intermediate states. This caused errors like:
- "no such column: sdk_session_id" (when columns already renamed)
- "table observations has no column named memory_session_id" (when not renamed)

Changes:
- Rewrite renameSessionIdColumns() to check each table individually
- Use safeRenameColumn() helper that handles all edge cases gracefully
- Deprecate migration 19 (repair migration) since 17 is now idempotent
- Update maintenance scripts to use memory_session_id column name
- Update test files to use new column names

Fixes column mismatch bug in v8.2.6+

* Merge origin/main into column-mismatch

---------

Co-authored-by: Alex Newman <thedotmack@gmail.com>

scripts/fix-all-timestamps.ts

@@ -18,7 +18,7 @@ interface CorruptedObservation {
   obs_created: number;
   session_started: number;
   session_completed: number | null;
-  sdk_session_id: string;
+  memory_session_id: string;
 }
 
 function formatTimestamp(epoch: number): string {
@@ -54,9 +54,9 @@ function main() {
         o.created_at_epoch as obs_created,
         s.started_at_epoch as session_started,
         s.completed_at_epoch as session_completed,
-        s.sdk_session_id
+        s.memory_session_id
       FROM observations o
-      JOIN sdk_sessions s ON o.sdk_session_id = s.sdk_session_id
+      JOIN sdk_sessions s ON o.memory_session_id = s.memory_session_id
       WHERE o.created_at_epoch < s.started_at_epoch  -- Observation older than session
          OR (s.completed_at_epoch IS NOT NULL
              AND o.created_at_epoch > (s.completed_at_epoch + 3600000))  -- More than 1hr after session