refactor(file_parser): simplify chunk ID generation in LinkedFileParser

Remove path and line numbers from chunk ID calculation to improve
cache stability. The chunk identity now uses only the content hash
instead of including path::start::end coordinates.

This change removes the documentation about chunk identity format
and updates the hash_text call to use only the text content.

reme2/component/file_parser/linked_file_parser.py

@@ -9,11 +9,6 @@ heading level) → recursive chunk (try whole subtree; on overflow walk
 children — body siblings pack as a run, subsections recurse). Leaf
 blocks (table / code / list / paragraph) split on internal boundaries
 and each piece is annotated ``[Part X/N]``.
-
-``chunk_chars`` constrains content only; the TOC skeleton is additive.
-Set ``embed_toc=False`` to drop the wrap. Chunk identity is
-``hash_text(path::start::end::text)`` for cache stability across
-re-parses of unchanged sections.
 """
 
 from dataclasses import dataclass, field
@@ -437,7 +432,7 @@ class LinkedFileParser(BaseFileParser):
         when ``embed_toc``, otherwise just ``content``."""
         text = _toc_join(before, content, after) if self.embed_toc else content
         return FileChunk(
-            id=hash_text(f"{path}::{start_line}::{end_line}::{text}"),
+            id=hash_text(text),
             path=path,
             start_line=start_line,
             end_line=end_line,