feat: Add mutable storage views for trailing fixed-layout fields including Vec and Option

[snawaz]

Summary

• Add FlexibleVec for trailing #[flexible = N] Vec<T> in fixed_offset_layout.
• Expose storage-backed capacity for decoded trailing flexible Vec fields.
• Add generated decode_mut(storage) and <field>_mut() APIs for mutable account/storage views.
• Support Vec-like mutation: push, pop, set, truncate, and clear.
• Document the storage-layout semantics and add coverage for scalar and fixed-layout Vec elements.

Testing

• cargo fmt
• cargo test -p wheels -p wheels-macros
• cargo clippy -p wheels -p wheels-macros --all-targets -- -D warnings
• cargo doc -p wheels --no-deps
• cargo doc -p wheels-macros --no-deps

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 411805d5-68b5-47ec-b268-c81e1f219c69

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}