feat(skills): expose bounded search and read tools

[andrei-hasna]

Summary

• expose namespaced skills.search and skills.read tools for turn-available skill packages
• preserve exact listing-provider provenance across opaque authority, package, and resource handles
• bound arguments, inspected results, serialized output, provider errors, lifecycle state, and telemetry previews
• add integration coverage for same-kind routing, custom authorities, host reads, hostile bounds, resource mismatch, and stale turns

Verification

• just test-fast -p codex-skills-extension
• just test -p codex-skills-extension
• just fix -p codex-skills-extension
• just fmt
• just bazel-lock-update
• just bazel-lock-check
• staged and committed-range secret and Co-Authored-By scans
• two independent adversarial reviews: no P0 or P1 findings

Station02 lacks OpenSSL development headers, so Rust compilation used a temporary vendored OpenSSL feature that was removed from the committed manifest and lockfile. CI should exercise the normal repository dependency configuration.

Residual risk

• the legacy public SkillProviders search seam remains kind-routed; these model tools use exact turn-scoped routes
• providers can allocate large result vectors before the model-tool boundary applies processing and output caps