fix(cli): embed the web UI as raw bytes instead of base64 strings

[Hona]

The CLI embedded each web UI asset as a base64 JavaScript string. Base64 adds a third, and with bytecode: true Bun keeps each string in both the source and the bytecode, so the web UI was stored twice. The assets now go into one binary archive that each build embeds as raw bytes.

Windows x64, OPENCODE_CHANNEL=prod	v2	This PR	Change
CLI (opencode.exe)	251.8 MB	206.8 MB	−44.9 MB
Desktop installer (NSIS)	272.3 MB	244.3 MB	−28.0 MB
Node CLI (opencode2-node.exe)	186.7 MB	177.7 MB	−9.0 MB

• The installer drops less than the CLI, because NSIS's LZMA already won back part of the base64.
• The Node build has no bytecode copy, so only the base64 third goes.

flowchart LR
  subgraph Before
    A[app/dist] -->|brotli → base64| B["virtual module<br/>{ key: 'G6kA…' }"] --> C["executable<br/>JS source + bytecode<br/>= 2 copies × 1.33"]
  end
  subgraph After
    D[app/dist] -->|brotli| E["app-archive.bin<br/>index + bodies"] --> F["executable<br/>1 raw copy"]
  end

Loading

Archive (app-archive.ts): a u32 index length, a JSON index of key → [offset, length], then the brotli bodies. decode returns views, so no asset is copied until a request decompresses it.

How each build embeds it

// Bun (script/build.ts): a file import, which bytecode leaves alone
import archive from ".cache/bun-app-archive.bin" with { type: "file" }
export default () => readFileSync(archive)

// Node (vite.node.config.ts): a SEA asset read in place; the prelude skips extracting it to tmp
export default () =>
  isSea()
    ? new Uint8Array(getRawAsset("app-archive.bin"))
    : readFileSync(path.join(process.env.OPENCODE_NODE_ASSETS_DIR, "app-archive.bin"))

• The CI hand-off between the Node jobs is unchanged: --app-archive=.cache/app-archive.bin is still one file, now binary.
• The server side (app-assets.ts, web-ui.ts) still decompresses each asset on request, as before.

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