Harden th up one-command local orchestration

[snissn]

Background

th up is the main dev loop, but failures around chain state, deploy drift, and manifest status can still be confusing.

Goal

Make th up a resilient one-command local workflow for build/deploy/preview/faucet.

Scope

• Improve preflight checks (RPC reachability, chain ID, wallet/deployer config sanity).
• Detect and explain manifest/deployment drift with clear remediation.
• Better chain mismatch guidance for generated UI + MetaMask.
• Consistent structured logs for each phase (build, deploy, preview, faucet).
• Fail with concise actionable next steps.

Implementation Notes

• Avoid hidden side effects; prefer explicit auto-fix messages.
• Preserve non-interactive behavior in CI mode.

Acceptance Criteria

• Common local misconfigs produce actionable diagnostics (not opaque stack traces).
• th up succeeds or fails with phase-specific context and remediation hints.
• Regression tests cover at least: wrong chain, missing deploy address, unreachable RPC.