docs: reframe value prop around precision/speed, update Node floor to 20, and expand language/framework coverage

- Benchmark table reordered to lead with tool calls, time, and file reads (the universal wins); cost and tokens moved right with a note that savings are scale-dependent, not a headline claim
- README/introduction/quickstart/installation messaging updated to "surgical context · fewer tool calls · faster answers" framing, dropping the "16% cheaper" headline
- Node engine floor raised from 18 to 20 in CLAUDE.md, package.json description updated
- `codegraph init` now creates and indexes in one step; the `-i` flag is retired (still accepted as a no-op)
- CLI reference expanded with new commands: `explore`, `node`, `unlock`, `daemon`, `telemetry`, `upgrade`, `version`, `help`
- MCP server docs clarified: single `codegraph_explore` tool exposed by default, others unlisted but re-enableable via `CODEGRAPH_MCP_TOOLS`
- Language support adds Objective-C, Astro, and R; framework routes adds Play, Vue Router/Nuxt, and Astro
- API reference documents lower-level exports and embedding requirements (Node 22.5+ for `node:sqlite`)
- Troubleshooting adds WSL/Windows dual-checkout guidance
- How-it-works updated: SQLite backend is now Node's built-in `node:sqlite` in WAL mode, not better-sqlite3/WASM

CLAUDE.md

@@ -29,7 +29,7 @@ npx vitest run __tests__/extraction.test.ts -t "TypeScript"
 
 `copy-assets` (called from `build`) copies `src/db/schema.sql` and all `src/extraction/wasm/*.wasm` files into `dist/`. **Any new SQL or grammar wasm must be copied or it won't ship.**
 
-Node engines: `>=18.0.0 <25.0.0`. There is a hard exit on Node 25.x (see `src/bin/node-version-check.ts`).
+Node engines: `>=20.0.0 <25.0.0`. There is a hard exit on Node 25.x and below 20 (see `src/bin/node-version-check.ts`).
 
 ## Architecture