chore: adopt Creed agent context

[shivros]

Summary

Adopts Creed as Rite's agents-only context source.

• Adds authored project, development, and workflow guidance rooted in Rite's Rust/Hydra architecture.
• Adds .creed/manifest.yaml with the agents target only and no skills, then commits generated AGENTS.md.
• Adds Creed drift validation to CI using github.com/techgodhq/creed@v0.3.0 and ignores .creed/.outputs/.

Verification

creed validate
creed sync
creed diff
cargo build --all-targets
cargo test --all-targets
cargo clippy --all-targets -- -D warnings
cargo fmt --all -- --check
cargo run -p rite-codegen -- check

All passed locally (36 Rust tests).

[shivros]

🤖 Automated Review Panel

Reviewer A — APPROVE

No correctness findings. Confirmed the agents-only/no-skills manifest, generated context, pinned Creed v0.3.0 CI drift job, ignore rule, and project conventions align with COD-414.

Reviewer B — APPROVE after ticket-context check

The review found no implementation defect. It suggested making the entire existing CI PR-only and pinning Go, but COD-414 requires landing via PR and a Creed version pin—not a PR-only CI trigger or a Go-version policy change. The existing push-to-main validation remains intentional; no unrelated CI alteration was made.

Both reviewers found the authored guidance truthful to Rite's Rust/Hydra architecture and deterministic Creed flow.

[shivros]

Auto-Merge Gate

Confidence: 0.94

COD-414's requested Creed adoption is implemented as a focused, agents-only context source: authored Rite guidance, an explicit no-skills manifest, committed generated AGENTS.md, ignored generated outputs, and a CI drift check pinned to Creed v0.3.0.

Validation observed: GitHub CI test and Creed context drift succeeded. Independent gate verification on the PR head passed git diff --check, cargo test --all-targets (36 tests), cargo run -p rite-codegen -- check, and cargo fmt --all -- --check.

Scope review: No secrets, deployment/cutover, destructive behavior, or manual-review marker detected. The PR directly satisfies the linked Linear acceptance criteria.