Proposed actions for symbol baseline diffs

[RyanCavanaugh]

I put the "needs investigation" groups at the top. Same procedure as #3540

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a curated groups.md document that categorizes .symbols.diff baseline differences, prioritizing “needs investigation” items similarly to #3540.

Changes:

• Introduces a new markdown report grouping 473 symbol baseline diffs by change type.
• Flags several categories as “Needs Investigation” / “Clear bug” and labels others as benign/intentional.
• Provides per-category lists of affected .symbols.diff files.

Show a summary per file

File	Description
groups.md	New categorization report for symbol baseline diffs, with investigation/benign labels and per-group file lists

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 5

[jakebailey]

These are all error cases with duplicate decls, so showing only one is really not a big deal as there's an error message and dts emit emitting (correctly) just one is not a problem

[jakebailey]

These are new error cases:

==== ex.d.ts (0 errors) ====
    declare var config: {
        fix: boolean
    }
    export = config;
    
==== test.js (1 errors) ====
    /** @param {import('./ex')} a */
                ~~~~~~~~~~~~~~
!!! error TS1340: Module './ex' does not refer to a type, but is used as a type here. Did you mean 'typeof import('./ex')'?
    function demo(a) {
        a.fix
    }
    

So fixing the error diff (which is not accepted) would fix this. But I seem to recall that this error diff was intentional

[andrewbranch]

Yeah, I remember @sandersn bringing this up. I don't mind being more strict about type/value confusion like this, but it seems like we've walked back a lot of similar breaks since then.