Implement local build from manifest

[KCDaemon]

Summary

• add local manifest loading for sh1pt build --from <path>
• add a build runner that selects manifest targets, loads target adapters, and invokes their build() methods
• wire the build command to produce real local artifacts while keeping cloud builds as the existing stub
• cover TS/JSON manifest loading, selected target builds, and unknown target errors

Verification

• corepack pnpm --filter @profullstack/sh1pt typecheck
• corepack pnpm exec vitest run packages/cli/src/build-project.test.ts packages/cli/src/input.test.ts
• corepack pnpm --filter @profullstack/sh1pt build
• corepack pnpm exec tsx packages/cli/src/index.ts build --from /Users/Yuli/ccgo/sh1pt-bounty-work/boilerplates/hello-world --target brew --channel beta

Closes #184
Part of #133