PHLEGM v6 - CHR File Tools / Session Confirmation checkpoint

CHR behavior
- Machine-facing CHR LOAD remains explicit: selected BIN/ZIP media is loaded into the active machine-defined Memory / Program CHR target only when the user requests CHR LOAD.
- Machine-facing CHR SAVE remains explicit: the current machine-defined CHR backing is pulled to a BIN only when the user requests CHR SAVE.
- OCR/remap is now a separate file-to-file workflow under the top-level CHR File Tools branch.
- Source BIN and Reference BIN are selected independently from the tree/icon model and must be different loose .BIN files.
- Source/reference layout, OCR confidence, and missing-glyph mode are explicit file-tool settings.
- CHR REMAP CREATE writes one new third BIN. It refuses to overwrite either input or an existing output.
- OCR recognition occurs in-memory during CREATE; no standalone OCR-generated layout artifact is written and no active machine Memory / Program state is consulted or changed.

Session behavior
- SESSION-SAVE and named SESSION-NEW require confirmation before replacing an existing non-blank-prefix .session.phlegm.
- cfg/sessions/.session.phlegm remains the automatic blank-prefix backup special case.
- SESSION-END requires confirmation before removing an existing session target. Cancel/No leaves the file untouched.
