refactor: add project application service seam

[xiayh0107]

Summary

• adds project-scoped ProjectQueryService and ProjectMutationService seams in rho-store;
• routes existing Run/Problem/Agent/Approval/Evidence/Artifact/Plot/cancellation Tauri paths through the shared services without changing command or response shapes;
• rejects blank project identity and requires explicit project scope for every mutation; and
• adds deterministic normal, empty, bounded, rejection, mutation, and two-project scenario coverage.

Stack dependency

This PR is stacked on Phase 2 PR #76 at exact head 12860008381910d8280d277ea1006ab04746b281. It should be rebased onto main after #76 merges; no #76 source is reimplemented here.

Governance

Owning contract: docs/plans/active-2026-08-20-project-application-service-seam-spec.md (APP-SVC1, D2/R2). Raw Store remains the sole persistence authority. No schema, migration, frontend/mock shape, public protocol, new mutation, version, NEWS, or release change.

Local validation

• cargo test -p rho-store --locked --no-fail-fast: 153 passed;
• scoped unused/dead-code Clippy enforcement: passed;
• cargo test -p rho-desktop --locked --no-fail-fast: 204 passed, one existing opt-in Keychain smoke ignored;
• cargo test --workspace --locked --no-fail-fast: passed;
• cargo build --workspace --locked: passed;
• affected Run History, Agent Conversation/concurrency, Evidence, and JS syntax contracts: passed;
• cargo fmt --all -- --check and git diff --check: passed;
• rho.bridge: 575 passed; rho.agent: 120 passed.

Hosted validation

Exact source head 69f073bbf00e711f7ae936840fce1528ed0cb12a:

• Draft Fast run 32361870469: passed;
• Ready Rust Compatibility run 32362297716: all six macOS/Ubuntu/Windows stable and Rust 1.88 legs passed, including packaged app smoke on every stable leg.

Independent review resolved unscoped Plot clearing, unused wrapper methods, incomplete query/mutation coverage, blank project identity, and stale direct-Store contract assertions.

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