feat: added markdown rendering

[justinwilkin]

No description provided.

[Copilot]

Pull request overview

Adds terminal markdown rendering for finalized agent output in the Forge TUI, using a new wrapper around charmbracelet/glamour and integrating it into the message commit path so rendered content reflows on resize.

Changes:

• Introduces pkg/executor/tui/markdown renderer package (plus unit tests) to render markdown to ANSI with width-aware reflow.
• Switches finalized agent messages (and loop-breaking full-inline tool results) to use markdown rendering via DisplayMessage.RenderFn.
• Updates Go dependencies and adds product/ADR documentation for the feature.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pkg/executor/tui/result_display.go	Exposes loop-breaking tool classification for downstream rendering decisions.
pkg/executor/tui/model.go	Adds mdRenderer to the TUI model.
pkg/executor/tui/messages.go	Adds newMarkdownMsg helper for width-aware render closures.
pkg/executor/tui/markdown/markdown.go	Implements markdown rendering (glamour) + code-block post-processing + render caching.
pkg/executor/tui/markdown/markdown_test.go	Adds unit tests for renderer behavior and width fallback.
pkg/executor/tui/init.go	Initializes mdRenderer in initialModel().
pkg/executor/tui/events.go	Renders finalized agent messages (and loop-breaking tool results) using markdown renderer closures.
go.mod	Bumps lipgloss and adds glamour + related indirect deps.
go.sum	Updates sums for new/updated dependencies.
docs/product/features/tui-markdown-rendering.md	Adds PRD-style documentation for markdown rendering feature.
docs/adr/0054-tui-markdown-rendering.md	Adds ADR describing the markdown rendering approach.

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