fix: token persistence, context windows, CSS tables/bullets/hr, image attachments

- Fix token count reset on app restart: persist realTokens in conversation.json
- Fix token/context window values: Studio 150K (summarize at 120K), Terminal 100K
- Fix table rendering in terminal tab: correct thead/tbody display model
- Fix copy button always top-right in Studio code blocks
- Add markdown horizontal rule (---) support in Studio and Terminal
- Fix bullet list double dot: remove CSS ::before duplicate bullet point
- Add image attachments support (VLM description, file mentions @file.ext)
- Add sudo detection with cache (sync.Once)
- Fix message content serialization (TextContent wrapper)
- Guide AI to use read_file instead of cat in studio prompt

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

internal/workflow/planner.go

@@ -27,7 +27,7 @@ func (p *Planner) GeneratePlan(ctx context.Context, goal string) ([]Step, error)
 	prompt := buildPlanPrompt(goal)
 
 	messages := []orchestrator.Message{
-		{Role: "user", Content: prompt},
+		{Role: "user", Content: orchestrator.TextContent(prompt)},
 	}
 
 	resp, err := p.orchestrator.SendWithTools(messages)