Keep SDK template manifests cargo-readable

[nicabarnimble]

Summary

• Keeps SDK cargo-generate template manifests parseable by Cargo before template rendering.
• Replaces invalid {{ package_name }} package names in template Cargo.toml files with valid default package names.
• Removes noisy Cargo git-dependency diagnostics for downstream consumers that pin patina-sdk from this repository.

Why / Design

Cargo scans Cargo.toml files in git dependencies before any cargo-generate rendering happens. The template manifests used raw Liquid placeholders in [package].name, which made Cargo report invalid package names whenever another repo depended on patina-sdk by git rev.

This keeps the template manifests syntactically valid as checked-in TOML. It does not change SDK manifest parsing or runtime behavior.

Changes

• sdk/template/Cargo.toml: valid default package name.
• sdk/template/checks/diagnostics/Cargo.toml: valid default diagnostics package name.
• sdk/template-legacy/Cargo.toml: valid default package name.

Validation

Local:

• cargo metadata --no-deps --format-version 1
• cargo test -p patina-sdk --no-default-features --features manifest
• cargo test --test template_end_to_end -- --nocapture — passed; cargo-generate e2e skipped because cargo generate is not installed locally.

GitHub Actions:

• Require Linked Issue — passed
• Lint — passed
• Test — passed
• Release — passed
• Retrieval Benchmark — skipped

Compatibility / Operations

• Downstream git dependencies can pin this exact rev to avoid Cargo diagnostics from SDK template manifests.
• No schema, SDK API, or runtime contract changes.

Follow-ups

• If cargo-generate package-name substitution remains required for these standalone SDK templates, add an explicit generation hook or migrate these files to a template-safe representation in a follow-up.