feat(tx-manifest): add request parser foundation

[lukachi]

• This PR suggests a bug fix and I've added the necessary tests.
• This PR introduces a new feature and I've discussed the update in an Issue or with the team.
• This PR is just a minor change like a typo fix.

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Summary

This is PR 1 of the ordered merge train that replaces the oversized #5.

It establishes the source-faithful request/parser foundation for @humid/tx-manifest:

• adds the package test and typecheck boundary;
• validates the existing six-part processConfidentialTransaction request contract;
• defaults broadcast to off and rejects caller-supplied fee fields;
• reads the selected action's required contract sources and prompted parameters;
• distinguishes wallet-funded inputs and newly created covenant outputs from covenant inputs that require state;
• carries the canonical p2pk manifest fixture unchanged.

The implementation is reconstructed from the existing feature/conf-tx lineage rather than introducing a parallel parser API.

Stack

• Base: master
• Next PR will target: feature/tx-manifest-parser

Deliberate exclusions

This PR does not add chain reads, transaction planning or construction, smplx/WASM integration, cross-covenant references/classes, issuance or blinding policy, comprehensive semantic validation, rendering, signing, broadcast, or release activation. Those land in later train cars.

Verification

• bun install --frozen-lockfile
• bun test packages/tx-manifest — 24 passed, 0 failed
• bun run typecheck:packages
• bun run typecheck
• bun run lint
• bunx oxfmt packages/tx-manifest packages/tsconfig.json packages/bun-test-env.d.ts package.json .oxfmtrc.json --check
• git diff master...HEAD --check