fix(keynote-2): split demo and bench CLI parsing

[joshua-spacetime]

Description of Changes

This cleans up the keynote-2 benchmark CLI and fixes the bench path that was broken after demo and bench started sharing a single parser. demo and bench now parse their own command grammars instead of sharing one import-time parser. This avoids bench inheriting demo-style validation and breaking on test-1 --connectors .... in addition, bench also uses the same cac-builder as demo now, and I've deleted the unused runner_1.ts.

API and ABI breaking changes

None

Expected complexity level and risk

3

Testing

Manually tested the following from templates/keynote-2:

• pnpm bench test-1 --seconds 10 --concurrency 50 --alpha 1.5 --connectors spacetimedb
• pnpm demo --seconds 1 --concurrency 5 --alpha 1.5 --systems spacetimedb --skip-prep --no-animation
• deno run --sloppy-imports -A src/demo.ts --help
• deno run --sloppy-imports -A src/cli.ts --help
• deno run --sloppy-imports -A src/cli.ts test-1 --seconds 10 --concurrency 50 --alpha 1.5 --connectors spacetimedb