feat(cli): select targets like rustup selects toolchains

[HalfSweet]

Stacked on #592 (← #591 ← #590 ← #588).

Summary

Every pocket check, compile and build named its target with --target or --host-profile, and the CLI recognized a framework by its package name.

Selection. A verb acts on the first of:

1. explicit: pocket +<id> <verb> (rustup's position), pocket <verb> +<id>, --target <id>, --host-profile <file> — two that differ are an error, a +id anywhere else before -- is an error;
2. POCKET_TARGET;
3. a directory override of the current directory or an ancestor (pocket override set <id> [--path DIR]);
4. the first entry of targets in the project's pocket.config.ts;
5. the user default (pocket default <id>).

None present stops with the five ways to name one. Each run prints pocket: target vita · directory override /work/game first. pocket build --all builds every project target in order.

Project configuration. PocketConfig gains targets: catalog ids, { target, manifest }, or { hostProfile, manifest } (the host profile's id names the target and may not equal a catalog id or a command word). The project configuration is the nearest pocket.config.ts above the manifest's directory — the file tools/build.ts reads theme from, so apps/note's own config keeps applying in a checkout — and the lookup stops there. tools/pocket.ts project bundles the file with @pocketjs/framework mapped to the resolved framework, so it evaluates in a project without node_modules (a Bun runtime plugin does not intercept that import; bundling does).

pocket show [--json] reports the framework and its source (POCKETJS_FRAMEWORK_ROOT, checkout, registry, git/file:/link: spec from bun.lock, or link → <path>), the project and its targets, the selection and why, the host, and the catalog with targets this host cannot install marked. Overrides and the default live in <config>/pocket-nexus/settings.json, written by rename.

Framework identity. A framework is any directory whose package.json carries "pocketjs": { "protocol": 1 } (added to this package); the name is not read, so a fork published under another name is recognized. The nearest of a checkout and an installed node_modules/@pocketjs/framework wins (checkout on a tie). The CLI passes --cli-protocol 1 and both sides stop on a mismatch.

pocket create writes pocket.config.ts; its package.json scripts name no target (pocket check, pocket build -- --release, pocket build --output dist/<name>.pocket for ESP-IDF).

New modules: tools/cli/framework.mjs, tools/cli/select.mjs, tools/targets/project.ts. Docs: the CLI reference gains Target selection, Project configuration, show, default, override and Switching to a fork.

Validation

bun test tests/cli.test.ts            # 21 pass: precedence of all five sources, both +id positions, conflicts, misplaced +id,
                                      #   nested overrides, project manifest/hostProfile entries, --all, protocol mismatch, show --json,
                                      #   framework marker/nearest/link resolution
bun test tests/targets-project.test.ts # 5 pass: nearest file stops the lookup, entry paths, diagnostics, POCKETJS_FRAMEWORK_ROOT with --no-install
bun run e2e:install                   # ok ×4: scaffolds select their target from pocket.config.ts against the read-only installed tarball

Every stage of bun tools/test.ts individually: unit 1085 pass / 1 fail (the class-diagnostics --strict-classes case, failing on this machine on main, passing in CI); all later stages pass. bunx tsc --noEmit: only the pre-existing errors in tests/runtime-glyphs.test.ts and tests/pocket3d-icon.test.ts.