refactor(idp): make find a paginated UEG shortcut - #831

Summary

pup idp find already queried the Unified Entity Graph, but its interface and guidance still made it look like a legacy lookup. This change keeps it as a small, service-first UEG shortcut while making idp entities query the primary interface for non-service and advanced graph work.

Changes

• Add --limit (default 10, range 1-100) and --cursor to idp find.
• Treat simple text literally before building the service-name wildcard query, so spaces and DSL operators cannot change its structure.
• Preserve explicit kind: or concrete ref: queries for compatibility while directing new non-service workflows to idp entities query.
• Share query-scope validation with idp entities query, including errors for ambiguous top-level OR, quoted kinds, and the unsupported free_text pseudo-field.
• Preserve the raw UEG JSON:API response and add accurate page count, truncation, and next-cursor guidance for agents.
• Update command help, examples, the service-catalog agent, and the dd-idp skill to describe find as a service-first paginated convenience command.
• Correct adjacent Service Catalog agent guidance: relations is read-only, and kind deletion takes a kind ID.

Testing

• cargo fmt --all -- --check
• cargo clippy --all-targets -- -D warnings
• cargo test -- --test-threads=1 ...: 2,015 passed, 0 failed, with two known environment-specific tests filtered
• Focused IDP, CLI parsing, and skill test suites
• Official skill validator for skills/dd-idp
• WASI and browser WASM builds
• Verified current CLI help exposes only relations list and names the kind-delete argument KIND_ID
• Live Datadog Staging smoke tests for service-name pagination, second-page cursor advancement, hyphenated names, literal spaces/operators, explicit team queries, concrete service refs, and guarded invalid queries/limits

Dependency audit

This change adds no dependencies. cargo audit --no-fetch reports four existing advisories in the upstream lockfile (h2, two rsa entries, and rustls); none were introduced or changed by this PR.