fix(compiler): tailor the parse error for invalid tag variables

[DylanPiercey]

parseVar parses a tag variable as (str)=>{} to reuse Babel's binding-pattern grammar and relayed Babel's raw message, so <div/my-el>hi</div> failed with Binding invalid left-hand side in function parameter list. — naming a parameter list the author never wrote. That family of parse errors is now rewritten to \my-el` is not a valid tag variable; use a JavaScript identifier or destructuring patternwith a docs link, and anerror-tag-var-invalidfixture pins it. Resolves the correspondingagent-feedback/dx.md` entry.

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Latest commit: 450a27c

The changes in this PR will be included in the next version bump.

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@marko/compiler	Patch

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Reviewing files that changed from the base of the PR and between 3b569b5 and 450a27c.

⛔ Files ignored due to path filters (4)

• packages/runtime-tags/src/__tests__/fixtures/error-tag-var-invalid/__snapshots__/error-compile-dom.debug.txt is excluded by !**/__snapshots__/** and included by **
• packages/runtime-tags/src/__tests__/fixtures/error-tag-var-invalid/__snapshots__/error-compile-dom.txt is excluded by !**/__snapshots__/** and included by **
• packages/runtime-tags/src/__tests__/fixtures/error-tag-var-invalid/__snapshots__/error-compile-html.debug.txt is excluded by !**/__snapshots__/** and included by **
• packages/runtime-tags/src/__tests__/fixtures/error-tag-var-invalid/__snapshots__/error-compile-html.txt is excluded by !**/__snapshots__/** and included by **

📒 Files selected for processing (5)

• .changeset/tag-var-parse-error.md
• agent-feedback/dx.md
• packages/compiler/src/babel-utils/parse.js
• packages/runtime-tags/src/__tests__/fixtures/error-tag-var-invalid/template.marko
• packages/runtime-tags/src/__tests__/fixtures/error-tag-var-invalid/test.ts

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.56%. Comparing base (3b569b5) to head (450a27c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3795   +/-   ##
=======================================
  Coverage   90.55%   90.56%           
=======================================
  Files         421      421           
  Lines       19849    19852    +3     
  Branches     3664     3664           
=======================================
+ Hits        17975    17979    +4     
+ Misses       1331     1329    -2     
- Partials      543      544    +1     

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