[FEATURE]: port V1 fuzzy edit matching to the V2 edit tool #51706

• I have verified this feature I'm about to request hasn't been suggested before.

The V2 edit tool matches oldString with a single literal indexOf scan, so any inexact match fails outright with "Could not find oldString". When a model reproduces oldString from memory and it is only nearly right — trailing whitespace, an indentation slip, an extra blank line — the edit fails, the model re-reads the file, and the call is retried.

V1 already handles these cases with seven lenient strategies, and a TODO in packages/core/src/tool/edit.ts has been tracking the port.

A PR is up that ports them as pure helpers in packages/core/src/tool/edit-match.ts, consulted only after exact matching returns zero, and that also fixes two open bugs in that logic: #41872 and #45199.

Previously requested in #32760, which was auto-closed for not following the issue template.