fix: add missing wakatime_stats table to canonical schema.sql (#2951)

[yachikadev]

Fixes #2951

Problem

The wakatime_stats table (added via migration 20260526000000_add_wakatime_stats.sql) was never backported to supabase/schema.sql. Self-hosters who bootstrap their database directly from schema.sql end up missing this table, causing: relation "public.wakatime_stats" does not exist
when WakaTime sync (/api/wakatime/sync) runs.

Changes

• Added the wakatime_stats table definition to supabase/schema.sql, matching the migration exactly (columns, FK to users(id), unique constraint on user_id, date).
• Enabled RLS and added the "Users can view their own wakatime stats" SELECT policy.
• Placed it alongside the other per-user caching tables (near local_coding_sessions / user_sponsor_metrics) for consistency.
• Fixed an unrelated stray ); after the leaderboard_cache table definition that was causing a SQL syntax error and breaking a fresh schema.sql run before it could even reach the new table.

Testing

• Ran schema.sql against a fresh local Supabase Postgres instance — all tables (including wakatime_stats) now create successfully.
• Verified user_id TEXT correctly matches users.id (also TEXT), so the foreign key resolves without casting issues.
• Confirmed migration file and schema.sql are now consistent for this table.

Notes for reviewer

The stray ); fix is a small drive-by fix needed to unblock testing this PR — happy to split it into a separate PR if preferred.

[github-actions]

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