feat: RAG, memory, plugins, lessons, file editor, split panes, Markdown rendering, PWA + UI overhaul

Major additions:
- RAG pipeline (indexing, chunking, search) with sidebar upload button
- Memory system with CRUD API
- Plugins and lessons modules
- MCP discovery and MCP server
- Advanced skills (auto-create, conditional, improver)
- Agent browser/image support, delegate, sessions
- File editor with CodeMirror in split panes
- Markdown rendering via react-markdown + KaTeX + highlight.js
- Raw markdown toggle
- PWA manifest + service worker
- Extension UI redesign with new design tokens and studio-style chat
- Pipeline API for chat streaming
- Mobile responsive layout

💘 Generated with Crush

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

internal/skills/conditional.go

@@ -0,0 +1,125 @@
+package skills
+
+import (
+	"strings"
+)
+
+type ActivationResult struct {
+	Active  bool
+	Reason  string
+	Skill   *Skill
+}
+
+func CheckActivation(skill *Skill, availableTools []string) ActivationResult {
+	if len(skill.RequiresTools) == 0 && len(skill.FallbackForTools) == 0 {
+		return ActivationResult{
+			Active: true,
+			Reason: "no activation conditions",
+			Skill:  skill,
+		}
+	}
+
+	toolSet := make(map[string]bool, len(availableTools))
+	for _, t := range availableTools {
+		toolSet[strings.ToLower(t)] = true
+	}
+
+	if len(skill.RequiresTools) > 0 {
+		for _, req := range skill.RequiresTools {
+			if !toolSet[strings.ToLower(req)] {
+				return ActivationResult{
+					Active: false,
+					Reason: "missing required tool: " + req,
+					Skill:  skill,
+				}
+			}
+		}
+		return ActivationResult{
+			Active: true,
+			Reason: "all required tools available",
+			Skill:  skill,
+		}
+	}
+
+	if len(skill.FallbackForTools) > 0 {
+		allPresent := true
+		for _, fb := range skill.FallbackForTools {
+			if !toolSet[strings.ToLower(fb)] {
+				allPresent = false
+				break
+			}
+		}
+		if allPresent {
+			return ActivationResult{
+				Active: false,
+				Reason: "primary tools available, fallback not needed",
+				Skill:  skill,
+			}
+		}
+		return ActivationResult{
+			Active: true,
+			Reason: "primary tools absent, activating as fallback",
+			Skill:  skill,
+		}
+	}
+
+	return ActivationResult{Active: true, Skill: skill}
+}
+
+func FilterActiveSkills(skillsList []Skill, availableTools []string) []Skill {
+	var active []Skill
+	for i := range skillsList {
+		result := CheckActivation(&skillsList[i], availableTools)
+		if result.Active {
+			active = append(active, skillsList[i])
+		}
+	}
+	return active
+}
+
+func GroupByReadiness(skillsList []Skill, availableTools []string) (available, needsSetup, unsupported []Skill) {
+	toolSet := make(map[string]bool, len(availableTools))
+	for _, t := range availableTools {
+		toolSet[strings.ToLower(t)] = true
+	}
+
+	for i := range skillsList {
+		s := &skillsList[i]
+		if len(s.RequiresTools) == 0 && len(s.FallbackForTools) == 0 {
+			missing := CheckDependencies(s)
+			if len(missing) == 0 {
+				available = append(available, *s)
+			} else {
+				needsSetup = append(needsSetup, *s)
+			}
+			continue
+		}
+
+		allReqMet := true
+		for _, req := range s.RequiresTools {
+			if !toolSet[strings.ToLower(req)] {
+				allReqMet = false
+				break
+			}
+		}
+		if allReqMet && len(s.RequiresTools) > 0 {
+			available = append(available, *s)
+		} else if !allReqMet && len(s.RequiresTools) > 0 {
+			unsupported = append(unsupported, *s)
+		}
+
+		if len(s.FallbackForTools) > 0 {
+			anyMissing := false
+			for _, fb := range s.FallbackForTools {
+				if !toolSet[strings.ToLower(fb)] {
+					anyMissing = true
+					break
+				}
+			}
+			if anyMissing {
+				available = append(available, *s)
+			}
+		}
+	}
+	return
+}