feat(daemon): complete Phase 2 Solo WSL core

[u9520107]

Summary:

• Add capability-driven Solo ALSA discovery, service state/revisions, bounded serial worker, and read-only daemon reconciliation.
• Add atomic disk profiles with device/schema binding; profiles never auto-apply.
• Add confirmed-write validation and one approved, reversible Direct Monitor boolean-write path.
• Add capability-domain safeguards, unavailable-control handling, and stable schema fingerprints.
• Add sanitized Solo fixture, WSL validation evidence, contributor prerequisites, and Phase 2/3 boundary docs.
• Limit CI push workflow to main; retain PR checks.

Validation: fmt, Clippy with warnings denied, 19 active tests; hardware tests remain ignored/manual. Native Linux/Pi, physical replug, integer/enum metadata, and numeric/enum writes move to Phase 3.