Clean up keynote-2 template README & DEVELOP

[bradleyshep]

Description of Changes

Refresh this stale PR against current master. Several original items were already applied upstream or conflict with recent keynote-2 work (#4616, #4647, #4678, #4682, #4698, #4703, #4743, #4745, #4753, #4757), so those are dropped. What remains is the still-relevant subset, rebased onto the current file structures.

README.md:

• Use pnpm run demo in Quick Demo (consistency with pnpm workspace)
• Add --concurrency and --alpha to demo options
• Add -- separator to docker compose run bench example
• Fix hardware config punctuation (add comma before "OS:")
• Remove redundant Quick Start section; replace with link to DEVELOP.md for prerequisites and CLI reference
• Add symlink for license

DEVELOP.md:

• Use pnpm run throughout (demo, prep, bench) instead of npm run
• Drop the -- pass-through after pnpm run bench (not needed with pnpm; matches the #4703 testing examples)
• Add Rust to Prerequisites
• Add explicit list of valid connector names (convex, spacetimedb, bun, postgres_rpc, cockroach_rpc, sqlite_rpc, supabase_rpc, planetscale_pg_rpc)
• Update CLI reference defaults to match methodology (seconds: 1→10, concurrency: 10→50)
• Condense docker compose run bench example to a single line with -- separator; fix npm prep → pnpm run prep

src/opts.ts: (CLI parsing moved here in #4703; original PR targeted the now-gone inline parsers in cli.ts/demo.ts)

• parseBenchOptions: bench --seconds default 1 → 10
• parseDemoOptions: demo --concurrency default 10 → 50

.env.example:

• Comment out USE_DOCKER=1 and SKIP_CONVEX=1 so demo defaults (convex, spacetimedb) work out of the box
• Comment out CONVEX_USE_SHARDED_COUNTER=1 (still a supported knob, just off by default)

Dropped as superseded by master

• Rust Client README section tweaks (heading capitalization, bottlnecked/then typo fixes) — section was removed by #4753
• Rename SPACETIME_METRICS_ENDPOINT → USE_SPACETIME_METRICS_ENDPOINT — master's src/config.ts still reads the original name
• Connector-name fixes in examples (sqlite → sqlite_rpc, postgres → postgres_rpc) — already corrected on master

API and ABI breaking changes

None.

Expected complexity level and risk

1 – Documentation and default-value changes. No functional changes to core logic.

Testing

• pnpm install in templates/keynote-2/ succeeds
• pnpm run bench --help / pnpm run demo --help render with valid-connec