fix(resources): restore v4 super.post create on collection posts

[ldt1996]

Restores v4-style instance post overrides that delegate to super.post on a bare collection path. The compatibility normalization runs before authorization and dispatch so the bare and slash forms both use collection/insert semantics, while default bare POST retains its 404 and loadAsInstance=false resources retain their distinct base-resource dispatch. Includes regressions for target parsing, default behavior, insert-vs-update authorization, and false-mode Resource/Collection separation.

Generated with GPT-5.6 Codex.

[gemini-code-assist]

Code Review

This pull request updates the Resource class to support v4-style instance posting on collection targets when no ID is present, and adds comprehensive unit tests for this behavior and RequestTarget collection semantics. The feedback advises updating the new test assertions to use assert.strictEqual instead of loose assert.equal to align with the repository's style guide.

[claude]

Reviewed; no blockers found.

[ldt1996]

unit failures are pre existing on main

[kriszyp]

Good catch. I think #1807 had this mostly covered, but the override case was missing, thank you for tracking down.

[kriszyp]

Ok, I guess GPT thinks this would be a lot safer to restrict this to this.loadAsInstance !== false.
_{🤖 Reviewed with GPT 5.6}

Addressed in 49a9319 with the loadAsInstance false guard and dispatch regression.

[kriszyp]

Review threads addressed.

[kriszyp]

Aligned with #1842: instance-loaded legacy bare POSTs normalize before authorization, while loadAsInstance=false custom handlers retain their existing Resource/Collection dispatch boundary. All review threads are addressed and CI is green.