feat: markdown rendering in chat via glamour

Assistant responses now rendered with full markdown support:
- Headers, bold, italic, strikethrough
- Code blocks with syntax highlighting
- Lists (ordered + unordered)
- Links, blockquotes
- Tables

Uses charm.land/glamour/v2 with dark theme. Renderer width
updates on terminal resize. Live markdown rendering during
streaming. Consistent ◆ prefix + indent for multi-line output.

go.mod

@@ -5,6 +5,7 @@ go 1.26.1
 require (
 	charm.land/bubbles/v2 v2.1.0
 	charm.land/bubbletea/v2 v2.0.2
+	charm.land/glamour/v2 v2.0.0
 	charm.land/lipgloss/v2 v2.0.2
 	github.com/BurntSushi/toml v0.3.1
 	github.com/VikingOwl91/mistral-go-sdk v1.2.1
@@ -19,22 +20,28 @@ require (
 	cloud.google.com/go v0.116.0 // indirect
 	cloud.google.com/go/auth v0.9.3 // indirect
 	cloud.google.com/go/compute/metadata v0.5.0 // indirect
+	github.com/alecthomas/chroma/v2 v2.14.0 // indirect
 	github.com/atotto/clipboard v0.1.4 // indirect
+	github.com/aymerick/douceur v0.2.0 // indirect
 	github.com/charmbracelet/colorprofile v0.4.2 // indirect
 	github.com/charmbracelet/ultraviolet v0.0.0-20260205113103-524a6607adb8 // indirect
 	github.com/charmbracelet/x/ansi v0.11.6 // indirect
+	github.com/charmbracelet/x/exp/slice v0.0.0-20250327172914-2fdc97757edf // indirect
 	github.com/charmbracelet/x/term v0.2.2 // indirect
 	github.com/charmbracelet/x/termios v0.1.1 // indirect
 	github.com/charmbracelet/x/windows v0.2.2 // indirect
 	github.com/clipperhouse/displaywidth v0.11.0 // indirect
 	github.com/clipperhouse/uax29/v2 v2.7.0 // indirect
+	github.com/dlclark/regexp2 v1.11.0 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/google/s2a-go v0.1.8 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.4 // indirect
+	github.com/gorilla/css v1.0.1 // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
 	github.com/lucasb-eyer/go-colorful v1.3.0 // indirect
 	github.com/mattn/go-runewidth v0.0.21 // indirect
+	github.com/microcosm-cc/bluemonday v1.0.27 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/tidwall/gjson v1.18.0 // indirect
@@ -42,6 +49,8 @@ require (
 	github.com/tidwall/pretty v1.2.1 // indirect
 	github.com/tidwall/sjson v1.2.5 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	github.com/yuin/goldmark v1.7.8 // indirect
+	github.com/yuin/goldmark-emoji v1.0.5 // indirect
 	go.opencensus.io v0.24.0 // indirect
 	golang.org/x/crypto v0.40.0 // indirect
 	golang.org/x/net v0.41.0 // indirect