feat(web): expose project trust diagnostics

[testikun]

Problem

The Trust work tracked by #343 needs more than a compact label: operators must be able to distinguish the active Session authority from the current Pi ProjectTrustStore decision. Treating a changed stored decision as an immediate authority change would be unsafe and inaccurate.

Value

Authenticated Web clients can explain trusted, explicitly denied, restricted, and unknown states while showing when a Session refresh is required for a changed Pi decision to take effect.

Approach

• Add a pure Trust projection that keeps Pi ProjectTrustStore and the active Session SettingsManager as separate facts.
• Report canonical workspace, presence of trust-gated project resources, stored trusted/denied/undecided decision, active Session trust, derived state, and refresh-required evidence.
• Read all facts from Pi-owned APIs; do not persist a Web permission policy.
• Fail closed to unknown when the workspace is unbound or Pi facts cannot be read.
• Expose authenticated GET /api/trust.

This is distinct from #360 compact snapshot state. It adds no trust-changing action or browser confirmation flow.

Validation

• bun run check
• bun run test: 1244 passed, 0 failed, 1 skipped; Vitest 30 passed
• focused Trust, Pi runtime, and Web Host tests: 42 passed
• git diff --check

Impact

• User-visible behavior: authenticated API consumers can inspect the active Trust boundary; no UI changes.
• Model-visible context/tools: none.
• Runtime/lifecycle: read-only Pi ProjectTrustStore and SettingsManager inspection.
• Persisted config/data: none.
• Compatibility/risk: additive optional controller method and endpoint; unavailable integrations return an explicit 501 response.

Related to #343.

[testikun]

CI context: both Linux Node jobs reach the pre-existing packed standalone Web CLI smoke, install the tarball, and then the server exits before announcing its origin (kill: No such process). Windows and the other checks pass. This matches the independently reproduced fresh-install peer-dependency failure tracked in #328, where npm selects Pi 0.85.0 and @earendil-works/pi-server cannot be resolved. Evidence: #328 (comment)

This PR does not change package metadata, CLI startup, or peer-dependency resolution. Its local check, focused tests, full Node suite, and Vitest suite pass as recorded in the PR body.