feat(ext/shared): glyph constants module for unified icon language

Centralizes the unicode glyphs used by sidebar nav and form action buttons
so popup and fullscreen surfaces stay in sync. Includes the REQUIRED_PILL
snippet used to replace the trailing-asterisk required-field marker.

Plan 2026-04-30 fullscreen UX phase 1 task 1.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

extension/src/shared/glyphs.ts

@@ -0,0 +1,22 @@
+//
+// Unicode glyph constants used across popup and fullscreen surfaces. All
+// glyphs are monochrome unicode (no emoji) so they render identically in the
+// codebase's monospace font. Pair each button glyph with a `title=` tooltip
+// at the call site for accessibility — the constants here are the visual,
+// not the affordance.
+
+export const GLYPH_REVEAL        = '⊙';   // password reveal toggle (hidden state)
+export const GLYPH_HIDE          = '⊘';   // password reveal toggle (revealed state)
+export const GLYPH_GENERATE      = '↻';   // password / passphrase generate
+export const GLYPH_FILL_FROM_TAB = '⤓';   // pull URL from active browser tab
+export const GLYPH_QR            = '◫';   // paste / upload QR image (TOTP)
+export const GLYPH_MONO          = '≡';   // toggle notes monospace font
+
+export const GLYPH_TRASH         = '▦';   // sidebar trash nav
+export const GLYPH_DEVICES       = '⌬';   // sidebar devices nav
+export const GLYPH_SETTINGS      = '⚙';   // sidebar settings nav
+export const GLYPH_LOCK          = '⏻';   // sidebar lock nav
+
+/// Inline HTML snippet for the required-field pill. Use after a label's text:
+///   `<label class="label" for="f-title">title ${REQUIRED_PILL}</label>`
+export const REQUIRED_PILL = '<span class="req-pill">required</span>';