Add MSER text-region detection (find text without OCR)

[JE-Chen]

shape_locator finds rectangles (not text) and locate_text needs an OCR engine and the exact string — neither answers "where is any text on screen?".

• find_text_regions (AC_find_text_regions): MSER glyph/word blobs as {x,y,width,height,area,center}, largest first. merge unions MSER's nested per-glyph regions; min_area/max_area/max_aspect filter; the whole-frame extremal region is dropped so a blank screen returns [].
• find_text_lines (AC_find_text_lines): groups glyph boxes within y_tolerance px into one box per line — crop and feed to OCR (faster + more accurate than full-frame), or detect a label appeared with no OCR dependency installed.
• cv2.MSER_create is base OpenCV (no contrib); reuses visual_match._haystack_gray (no copied loader); injectable haystack → headless-testable on synthetic two-row text. Wired through all 5 layers + headless test + EN/Zh docs + WHATS_NEW. Qt-free.

[codacy-production]

Not up to standards ⛔

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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