feat: add form response submition endpoint and forms filtering

internal/db/sqlc/queries/responses.sql

@@ -0,0 +1,24 @@
+-- name: CreateFormResponse :one
+INSERT INTO form_responses (form_id, user_id)
+VALUES ($1, $2)
+    RETURNING *;
+
+-- name: GetFormResponsesByFormID :many
+SELECT * FROM form_responses
+WHERE form_id = $1
+ORDER BY submitted_at DESC;
+
+-- name: FormHasResponses :one
+SELECT EXISTS (
+    SELECT 1 FROM form_responses WHERE form_id = $1
+) AS has_responses;
+
+-- name: CreateResponseAnswer :one
+INSERT INTO response_answers (response_id, question_id, form_id, answer_text)
+VALUES ($1, $2, $3, $4)
+    RETURNING *;
+
+-- name: GetAnswersByResponseID :many
+SELECT * FROM response_answers
+WHERE response_id = $1
+ORDER BY id ASC;