feat(cli): add [lint.extra] for per-file lint rules

[Kamirus]

Problem

All lint rules currently apply uniformly to every .mo file in a project. There's no way to enforce file-specific constraints — e.g. "Types.mo must only contain type declarations" or "migration files must not expose public functions other than migration()" — without maintaining separate lintoko invocations outside of mops lint.

Solution

Add a [lint.extra] section to mops.toml that maps file globs to additional rule directories:

[lint.extra]
"src/main.mo" = ["lint/no-types"]
"src/Types.mo" = ["lint/types-only"]
"migrations/*.mo" = ["lint/migration-only", "lint/no-types"]

Each entry triggers a separate lintoko invocation on matched files, in addition to the base rules that always run on all files.

Design decisions

• Run all, then fail — all runs (base + extra) execute even when earlier runs find errors, so users see every lint failure in a single pass
• --rules CLI flag only affects the base run — [lint.extra] entries always run independently, keeping CLI overrides scoped to the main rule set
• Filter intersection — mops lint <filter> scopes extra runs to the same file set as the base run (no surprising out-of-scope linting)
• Missing rule dir → hard error; no matched files → warning and skip
• [lint] args and CLI extra args are forwarded to all runs (base + extra) via a shared buildCommonArgs helper
• Success message deferred — "Lint succeeded" only printed after all runs pass

Test plan

• All 11 lint tests pass (6 existing + 5 new snapshot tests)
• Pre-commit hooks pass (prettier, eslint, tsc, svelte-check)
• Manual smoke test: validated example tree-sitter queries (no-types, types-only, migration-only) against real Motoko files with lintoko 0.7.0
• Verified run-all behavior: base failure does not prevent extra runs from executing