Add RemoveUnicodeCharacters SE5 plugin

[niksedk]

Summary

• Adds a new SE5 plugin that detects non-ANSI characters (code point > 255) and lets the user remove or replace each one through a checkable preview window with an inline editable "Replace with" textbox per row.
• Replacements are persisted across runs via the SE5 plugin Settings round-trip; built-in defaults map ♪/♫ to # and everything else to empty (= remove).
• Adds the matching multi-rid build workflow (mirrors word-censor.yml) and the catalog entry in se5-plugins.json.

UI

• One row per unique character: checkbox, hex code (U+XXXX), glyph, count, editable replacement, line numbers.
• Toolbar: Select all, Select none, Google selected (opens a hex-code search in the system browser).
• Apply replaces in a single pass per affected line, reports Replaced N occurrence(s) across M line(s) to SE's status bar, and registers a "Remove Unicode characters" undo entry.

Test plan

• CI build passes for all six RIDs (win/linux/osx × x64/arm64).
• Manually run on an SRT with ♪, ♫, …, and accented letters — selected lines only.
• Edit a replacement, Apply, re-run — confirm the edited value is restored from settings.
• Verify the entry appears in SE's Get plugins dialog after a release tag is published.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds a new SE5 Avalonia plugin RemoveUnicodeCharacters that detects non-ANSI characters (code point > 255), shows a checkable preview with per-character editable replacements, persists replacements through the SE5 settings round-trip, and applies them as a single subtitle update with undo metadata. Also adds the matching multi-RID GitHub Actions workflow and a catalog entry in se5-plugins.json.

Changes:

• New SE5 plugin project (App, MainWindow, UnicodeCharRow, csproj, manifest, plugin.json, README) mirroring the WordCensor preview/apply pattern, with built-in defaults ♪/♫ → # and a "Google selected" action.
• New remove-unicode-characters.yml workflow that mirrors word-censor.yml for six RIDs with optional minor-bump release flow.
• New catalog entry in se5-plugins.json pointing at the se5-remove-unicode-characters-v1.1 release artifacts.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
se5/RemoveUnicodeCharacters/UnicodeCharRow.cs	Observable row model with checkbox/replacement/hex/glyph/lines metadata.
se5/RemoveUnicodeCharacters/RemoveUnicodeCharacters.csproj	Avalonia/.NET 8 project referencing Plugin-Shared.
se5/RemoveUnicodeCharacters/Program.cs	Entry point delegating to PluginBootstrap.Run<App>.
se5/RemoveUnicodeCharacters/plugin.json	Plugin manifest (apiVersion 1, version 1.0.0, dotnet runtime).
se5/RemoveUnicodeCharacters/MainWindow.axaml(.cs)	Preview window: scan, build rows, apply replacements, persist settings, Google search.
se5/RemoveUnicodeCharacters/App.axaml(.cs)	Avalonia app shell with FluentTheme; creates MainWindow.
se5/RemoveUnicodeCharacters/app.manifest	Windows DPI-awareness manifest.
se5/RemoveUnicodeCharacters/README.md	UI and build documentation.
se5-plugins.json	Catalog entry pointing at v1.1 release artifacts.
.github/workflows/remove-unicode-characters.yml	Multi-RID self-contained publish + optional release workflow.

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