Preview Tabler icons in the mobile app (#8109)

## Summary

Preview buzz-app's Tabler icon style in the mobile app, replacing
app-drawn Lucide glyphs across channels, messages, activity, search, and
settings. A shared `BuzzIcons` mapping uses the bundled Tabler 3.46.0
outline font, matching buzz-app's version, with its MIT license and
source documented.

Native UIKit controls retain SF Symbols. The former 300/500 navigation
glyphs use Tabler's standard outline; existing selection colors and
labels remain.

### Related issue

No matching Tabler mobile migration issue or PR found. Related native
iOS controls: #8055.

### Testing

- Pre-push mobile analysis, formatting, file-size checks, and the full
mobile test suite passed.
- 194 focused widget tests passed, including channels, home, search,
settings, and message content.
- Light and dark community-settings renders inspected.
- Signed iPhone Release build succeeded; installed and launched as Buzz
Tabler on a physical iPhone.
- Full `just ci` attempted; stopped during Rust clippy compilation
because the Mac ran low on disk space. Full repository validation is not
claimed.

Signed-off-by: kenny lopez <klopez4212@gmail.com>

mobile/assets/fonts/README.md

@@ -50,3 +50,16 @@ this check. PR images may be cropped afterward for readability.
 artifacts in the existing Flutter test lane. Restoring either original font or
 changing any other font data fails CI. When upgrading Inter, verify the
 transformation and native rendering before updating the expected digests.
+
+## Tabler mobile preview
+
+`TablerIcons.ttf` is the unmodified outline webfont from
+`@tabler/icons-webfont@3.46.0`, matching buzz-app's Tabler dependency version.
+Source: https://cdn.jsdelivr.net/npm/@tabler/icons-webfont@3.46.0/dist/fonts/tabler-icons.ttf
+The upstream MIT license is bundled in `TablerIcons-LICENSE.txt`.
+
+`lib/shared/theme/buzz_icons.dart` maps the existing mobile semantic names to
+Tabler glyphs using the package's `dist/tabler-icons.css` codepoints. Native
+UIKit controls retain SF Symbols. Lucide's 300/500 navigation weight variants
+both map to Tabler's standard outline; selection still uses the existing color
+and label treatment.

mobile/assets/fonts/TablerIcons-LICENSE.txt

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020-2026 Paweł Kuna
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.