* feat: add ClickHouse database engine support

Add ClickHouse support using the github.com/sqlc-dev/doubleclick parser library.

New files in internal/engine/clickhouse/:
- parse.go: Parser implementation using doubleclick
- convert.go: AST converter from doubleclick to sqlc AST
- format.go: ClickHouse-specific SQL formatting
- catalog.go: Catalog initialization
- stdlib.go: Standard library functions
- reserved.go: Reserved keywords
- utils.go: Helper functions
- parse_test.go: Unit tests

Supported SQL operations:
- SELECT with JOINs, subqueries, CTEs, window functions
- INSERT with VALUES and SELECT subquery
- UPDATE and DELETE
- CREATE TABLE, ALTER TABLE, DROP TABLE, TRUNCATE

Co-Authored-By: Claude <noreply@anthropic.com>

* chore: remove test file

Co-Authored-By: Claude <noreply@anthropic.com>

* chore: return empty function set from stdlib

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: move ClickHouse support to parse command only

Remove ClickHouse from compiler/engine.go and config.go.
Add --dialect clickhouse support to the sqlc parse command.

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

…y with 4 updates (sqlc-dev#4284)

Bumps the production-dependencies group with 4 updates in the / directory: [github.com/google/cel-go](https://github.com/google/cel-go), [github.com/lib/pq](https://github.com/lib/pq), [github.com/ncruces/go-sqlite3](https://github.com/ncruces/go-sqlite3) and [github.com/pganalyze/pg_query_go/v6](https://github.com/pganalyze/pg_query_go).


Updates `github.com/google/cel-go` from 0.26.1 to 0.27.0
- [Release notes](https://github.com/google/cel-go/releases)
- [Commits](google/cel-go@v0.26.1...v0.27.0)

Updates `github.com/lib/pq` from 1.10.9 to 1.11.1
- [Release notes](https://github.com/lib/pq/releases)
- [Changelog](https://github.com/lib/pq/blob/master/CHANGELOG.md)
- [Commits](lib/pq@v1.10.9...v1.11.1)

Updates `github.com/ncruces/go-sqlite3` from 0.30.4 to 0.30.5
- [Release notes](https://github.com/ncruces/go-sqlite3/releases)
- [Commits](ncruces/go-sqlite3@v0.30.4...v0.30.5)

Updates `github.com/pganalyze/pg_query_go/v6` from 6.1.0 to 6.2.2
- [Changelog](https://github.com/pganalyze/pg_query_go/blob/main/CHANGELOG.md)
- [Commits](pganalyze/pg_query_go@v6.1.0...v6.2.2)

---
updated-dependencies:
- dependency-name: github.com/google/cel-go
  dependency-version: 0.27.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: production-dependencies
- dependency-name: github.com/lib/pq
  dependency-version: 1.11.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: production-dependencies
- dependency-name: github.com/ncruces/go-sqlite3
  dependency-version: 0.30.5
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: production-dependencies
- dependency-name: github.com/pganalyze/pg_query_go/v6
  dependency-version: 6.2.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: production-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>