Tags: add a visual icon picker for tag icons

[StuartMeeks]

What & why

Tag icons were set by typing a raw Segoe Fluent Icons glyph or its hex code point — unfriendly, and with no way to browse what's available. This adds a visual picker: a searchable grid of icons you click to choose, driven from the Tags view.

Smoke-tested by Stuart and looks good.

How it works

• Each row in the Tags view gains a Choose… button that opens GlyphPickerDialog — a virtualised GridView of FontIcons with a search box that filters by name, keyword or code point (e.g. folder, run, E80F). Pick via single-select + Choose, or double-tap a glyph.
• The free-text field stays as the escape hatch for pasting a glyph directly. Selection still flows through the existing GlyphInput.Resolve and stored-character model, so persistence is unchanged.
• The catalogue is a curated 50-glyph set in appsettings.json beside the app (code point + friendly name + search keywords). The picker re-reads the file each time it opens, so adding/removing entries takes effect with no rebuild. Code points were grounded against the official Segoe Fluent Icons font list rather than guessed.

Architecture

Respects the one-way Core → App boundary:

• Core (UI-free, testable): GlyphCatalogueEntry model, IGlyphCatalogueProvider, GlyphPickerViewModel (all search/selection logic), new IShellInteractions.PickGlyphAsync, and a ChooseGlyphCommand on TagIconRowViewModel.
• App (WinUI): GlyphCatalogueProvider (reads/resolves the JSON, degrades to an empty catalogue rather than throwing on a bad edit), GlyphPickerDialog, DI registration, and the WindowsShellInteractions implementation.

Scope kept to the first cut per the TODO: tags only — CLI icons stay image/identicon.

Testing

• 11 new Core unit tests: GlyphPickerViewModelTests (sort, name/keyword/code-point search, no-results, preselection by glyph and typed code point, selection-dropped-on-filter, empty catalogue) and TagIconsViewModelTests (Choose command stores / cancels / no-ops without interactions). All 226 Core tests pass.
• WinUI head compile-verified on the Windows build agent: 0 warnings, 0 errors.

Notes for later

• A Velopack update overwrites the install directory, so user edits to appsettings.json won't survive an update. Fine for the shipped default; if catalogue customisation becomes a real need, LocalAppData is the durable home.
• Search is substring matching across name + keywords + code point — plenty for 50 entries. Revisit fuzzy search only if the catalogue grows large.

🤖 Generated with Claude Code