fix(extraction): capture & clean docstrings across all README languages (#780) (#806)

* fix(extraction): capture docstrings for export/const/decorator-wrapped symbols (#780)

getPrecedingDocstring walked previousNamedSibling from the EMITTED
declaration node, so it only found a leading comment when the comment was
a direct sibling of that node. For a declaration nested under a wrapper —
`export class X` / `export const f = () => {}` (export_statement /
lexical_declaration), a plain const arrow (variable_declarator), or a
decorated Python def/class (decorated_definition) — the comment is a
sibling of the WRAPPER, so the inner node had no preceding comment and
the docstring was stored as NULL.

Climb out through the wrapper node(s) before scanning for the comment.
Each wrapper holds exactly one declaration, so this can't mis-attribute a
comment to a sibling (verified: an uncommented method does NOT inherit its
class's comment). Also strip leading `#` from Python/Ruby/shell line
comments, which the cleanup chain missed (Python docstrings used to keep
their `#`).

Query/extraction-layer change to a parse helper; re-index to pick up
docstrings on already-indexed files. Verified on the reporter's JS/TS and
Python repros (8/8 now captured) plus over-walk controls; +3 tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(extraction): clean comment markers across all supported languages (#780)

Validating docstring capture across every README language surfaced that
the marker cleanup only knew C-style `//` and `/* */`, plus the `#` added
earlier this branch. Doc comments in other styles were captured but left
their markers in the stored text:

  - Rust/Swift/Kotlin doc lines `///` and `//!`  -> leading `/` / `!` leaked
  - Lua/Luau `--` and `--[[ ]]`                  -> not stripped
  - Pascal `{ }` and `(* *)`                     -> not stripped

Extract the cleanup into cleanCommentMarkers() and handle every style.
Paired block delimiters are stripped only when the comment OPENS with one,
so a line comment that happens to end with `}` / `*)` / `]]` is never
truncated; per-line markers stay anchored at line start.

Validated end-to-end (extract -> index -> codegraph_node output) across
all 19 tree-sitter code languages plus Svelte/Vue `<script>` blocks: every
one now stores and returns a clean docstring. +1 cross-language test.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -29,6 +29,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixes
 
+- Doc comments are now captured for exported, `const`-assigned, and decorated declarations, and the documentation a symbol carries is now clean across every supported language. Previously a comment above `export class X`, `export const fn = () => …`, a plain `const fn = () => …`, or a decorated Python `def`/`class` (`@app.route(...)`, `@dataclass`) was dropped entirely — only comments directly above a plain declaration were kept. CodeGraph now finds the comment through the `export` / `const` / decorator wrapper. Comment-marker cleanup was also rounded out for every language CodeGraph supports: Rust/Swift/Kotlin doc lines (`///`, `//!`), Python/Ruby/shell `#`, Lua/Luau (`--` and `--[[ ]]`), and Pascal (`{ }` and `(* *)`) no longer leave stray markers in the stored text — validated end-to-end across all 19 code languages plus Svelte/Vue `<script>` blocks. (#780). Thanks @caleb-kaiser.
 - Go method calls made through a chained factory function now resolve to the correct type. A call like `New().Method()` used to drop the receiver, so the chained method attached to a same-named method on an unrelated type — or didn't resolve. CodeGraph now captures Go return types (a pointer `*Foo` resolves to `Foo`, and a multi-return `(*Foo, error)` to its first result), infers the chained receiver's type from what the factory function returns, and resolves the method on it — including methods promoted from an embedded struct — creating the edge only when the type or an embedded type genuinely has the method. Existing Go indexes should be re-indexed (`codegraph index -f`) to benefit. (#750) (Go)
 - Scala method calls made through a companion-object factory, a fluent chain, or a case-class `apply` now resolve to the correct type. A call like `Foo.create().bar()` or `Builder(cfg).bar()` used to drop the receiver, so the chained method silently attached to a same-named method on an unrelated type — most often mis-attributing a standard-library `Option` / `Iterator` `.map` / `.flatMap` / `.foreach` onto your own same-named class. CodeGraph now captures Scala return types (a generic `List[Foo]` resolves to its container `List`, a qualified `pkg.Foo` to `Foo`), infers the chained receiver's type from what the inner call returns or constructs, and resolves the method on it — including methods inherited from a trait the type extends — creating the edge only when that type or one of its traits genuinely has the method (so a wrong inference produces no edge instead of a misleading one). Existing Scala indexes should be re-indexed (`codegraph index -f`) to benefit. (#750) (Scala)
 - Rust method calls made through a chained associated function now resolve to the correct type. A call like `Foo::new().bar()` or `Foo::with(cfg).build()` used to drop the receiver, so the chained method silently attached to a same-named method on an unrelated type — or didn't resolve. CodeGraph now captures Rust return types (`-> Self` resolves to the implementing type), infers the chained receiver's type from what the associated function returns, and resolves the method on it — including methods provided by a trait the type implements (via the new `impl Trait for Type` relationships) — creating the edge only when the type or one of its traits genuinely has the method. Existing Rust indexes should be re-indexed (`codegraph index -f`) to benefit. (#750) (Rust)