Address review findings: context menu permissions, font submenu, parity notes, and lockfile

- Grey out restricted page context-menu actions (editing, annotation, assembly, printing) on protected PDFs.
- Group installed fonts by family with search, max height, and scroll area in the format panel. Prevent row cutoff in font dropdown.
- Document Unicode character conversion behavior for superscript and subscript in parity notes.
- Revert unintended clipboard-win bump in Cargo.lock back to 5.4.1.

parity/acrobat-features.toml

@@ -1947,11 +1947,11 @@ title = "Superscript and subscript"
 area = "C"
 tier = "P2"
 milestone = "M7"
-status = "planned"
-commands = []
+status = "partial"
+commands = ["edit.edit_text"]
 tools = []
-evidence = []
-notes = ""
+evidence = ["crates/ui-egui/src/edit_text_ui.rs::superscript_and_subscript_conversion"]
+notes = "Toggled in the Format text panel for the selection. Uses Unicode superscript and subscript forms (2 ↔ ²) rather than text rise (Ts) and font scaling, so the font must provide the corresponding glyphs and extracted text contains the Unicode characters."
 
 [[feature]]
 id = "edit.paragraph-alignment"