[feature-request] A frontend selector for TypeScript declarations, so naming rules reach .ts identifiers

[jessegall]

Proposal:
SentenceIdentifierDetector is a Backend\Detector over PhpParser, so it judges PHP identifiers only. ProseFileNameDetector bridges to TypeScript because a file NAME needs no parser, but an identifier inside a .ts module does, and the writing-detectors skill forbids regexing code structure. Vue\Codebase::whereTypeDeclaration() reaches standalone .ts type declarations, so interface and type NAMES are already judgeable — but a function, a const and a local are not, and those are most of a plain TypeScript client. A selector over .ts declarations (function, const, class, method, parameter) would let the naming sin cover the frontend with the same rule rather than a second, weaker one.

Filed via commandments feature-request from a consumer project.

[jessegall]

Identifier-level rules now reach .ts declarations.

whereFunction(), whereClass(), whereMethodDeclaration(), whereVariable(), whereField() and whereParameter() all yield matches exposing name() and location(), so a naming sin covers the frontend with the SAME rule rather than a second, weaker one. A function, a const, a class method and a parameter are each reachable, and a method's parameters are found without the selector knowing they sit inside a class — children() is the one hook the walk descends through.
Shipped in v4.243.0 (query surface) and v4.244.0 (namespace).

The frontend engine now reads TypeScript as a language rather than as a place types happen to live.

• Bodies are parsed. Statements are nodes — if, switch, loops, return, throw, try/catch, blocks, expression statements — and classes are nodes with their methods, fields and constructor parameter properties. The JS inside every one of them goes to the expression parser the template engine already owned, so there is one expression language, not a second.
• Everything knows where it is. Every Ts node and every Expr records the byte range it was parsed from, so a match reports a real file:line. A <script> block is told the offset it begins at, so its nodes report lines in the surrounding .vue file rather than in the block.
• Selectors, named as the backend names them so a rule reads the same whichever language it judges: whereClass, whereFunction, whereMethodDeclaration, whereVariable, whereField, whereParameter, whereStatement, whereIf, whereSwitch, and over expression space whereCall, whereMember, whereCoalesce, whereTernary, whereLiteral. Each opens a query, where/reject narrow it, a terminal returns located matches.
• TypeScript is its own domain. The lexers, parser, AST and expression tree moved out of Vue\ to Ts\. Ts\ contains zero references to Vue\; an SFC embeds TypeScript, so Vue depends on Ts and never the reverse. Ts\Query and Ts\NodeMatch are the frontend twins of Ast\Query and Ast\NodeMatch.

Codebase::scan() on a directory containing only .ts files parses them all with no component anywhere — verified as a test.