Fix BASE_URL config loading, add tasks/projects; robust .env path resolution

- Config: try ENV_FILE, .env, ../.env for loading; trim trailing slash from BaseURL
- Log BASE_URL at server startup for verification
- .env.example: document BASE_URL
- Tasks, projects, tags, migrations and related API/handlers

Made-with: Cursor

sqlc/queries/task_webhooks.sql

@@ -0,0 +1,16 @@
+-- name: CreateTaskWebhook :one
+INSERT INTO task_webhooks (id, owner_id, url, events, secret)
+VALUES ($1, $2, $3, COALESCE($4, '[]'), $5)
+RETURNING *;
+
+-- name: GetTaskWebhookByID :one
+SELECT * FROM task_webhooks
+WHERE id = $1 AND owner_id = $2;
+
+-- name: ListTaskWebhooksByOwner :many
+SELECT * FROM task_webhooks
+WHERE owner_id = $1
+ORDER BY created_at DESC;
+
+-- name: DeleteTaskWebhook :exec
+DELETE FROM task_webhooks WHERE id = $1 AND owner_id = $2;