Add inverse_of tracking and admin question management

- Add inverse_of column support for question pair linking
- Enhance admin questions page with bulk operations
- Add DB migrations for inverse_of and FK indexes
- Update pack generator docs for inverse linking
- Improve Docker configs for admin app

apps/supabase/migrations/20260111100000_add_inverse_of_to_questions.sql

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+-- Add inverse_of column to questions table
+-- This allows tracking when questions are inverses of each other
+-- (e.g., "Do you want to give X?" and "Do you want to receive X?")
+-- The "primary" question has inverse_of = NULL
+-- The "secondary" (inverse) question points to its primary
+
+-- Add the column
+ALTER TABLE questions
+ADD COLUMN inverse_of UUID REFERENCES questions(id) ON DELETE SET NULL;
+
+-- Add a comment to document the column
+COMMENT ON COLUMN questions.inverse_of IS 'References the primary question that this question is an inverse of. Used to track question pairs (e.g., give/receive). Primary questions have inverse_of = NULL, secondary questions point to their primary.';
+
+-- Create an index for efficient lookups
+CREATE INDEX idx_questions_inverse_of ON questions(inverse_of) WHERE inverse_of IS NOT NULL;
+
+-- Create a function to get unique question count for a pack
+-- Unique count = questions that are NOT inverses of another question (i.e., inverse_of IS NULL)
+CREATE OR REPLACE FUNCTION get_pack_unique_question_count(pack_uuid UUID)
+RETURNS INTEGER
+LANGUAGE SQL
+STABLE
+AS $$
+  SELECT COUNT(*)::INTEGER
+  FROM questions
+  WHERE pack_id = pack_uuid
+    AND inverse_of IS NULL
+    AND deleted_at IS NULL;
+$$;
+
+-- Grant execute permission to authenticated users
+GRANT EXECUTE ON FUNCTION get_pack_unique_question_count(UUID) TO authenticated;
+
+-- Create a view to get pack stats including both total and unique counts
+CREATE OR REPLACE VIEW pack_question_stats AS
+SELECT
+  pack_id,
+  COUNT(*) FILTER (WHERE deleted_at IS NULL) AS total_questions,
+  COUNT(*) FILTER (WHERE inverse_of IS NULL AND deleted_at IS NULL) AS unique_questions,
+  COUNT(*) FILTER (WHERE inverse_of IS NOT NULL AND deleted_at IS NULL) AS inverse_questions
+FROM questions
+GROUP BY pack_id;
+
+-- Grant select on the view
+GRANT SELECT ON pack_question_stats TO authenticated;