feat(web): define ChatEvent discriminated union, eliminate all any sites (R9)

Created web/src/lib/types.ts with discriminated unions for SSE event
payloads: ChatEvent (7 variants: session, tool_use, tool_result,
text_delta, text, done, error), ToolCallResult, MessageContent, and
typed data shapes for live events (PlanProposedData, PlanStepEventData,
QuestionRaisedData, QuestionAnsweredData, EntityTouchedData,
HealthChangedData) plus WailsGlobal for the desktop bridge.

Replaced all ~15 `any` sites across 7 files:
- api.ts: Message.content any -> MessageContent | string; removed local
  ChatEvent interface (now imported from types.ts as a discriminated
  union); JSON.parse cast to ChatEvent.
- stores/chat.ts: removed local ToolCallResult interface (imported from
  types.ts, re-exported for backward compat); extractApprovals accesses
  args with typeof guards instead of implicit any access; toChatMessages
  handles string|object Message.content cleanly.
- stores/activity.ts: update_plan_step seq/status extracted via typeof
  guards instead of `as any` casts; toolActivityLabel uses a str() helper
  for safe string extraction from unknown args.
- stores/workspace.ts: applyPlanStepEvent takes PlanStepEventData;
  applyEvent casts data to Record<string, unknown>; switch cases cast to
  typed interfaces (PlanProposedData, QuestionRaisedData, etc.) instead
  of `as any`; applyHealthChanged uses HealthChangedData.
- Config.svelte: (window as any).wails -> typed WailsGlobal cast;
  catch (e: any) -> catch (e: unknown) with instanceof Error check.
- utils.ts: WithoutChild/WithoutChildren `any` -> `unknown`.
- vite.config.ts: authProxy proxy/proxyReq `any` -> ProxyOptions type.

Result: eslint no-explicit-any warnings dropped 12 -> 0. Tests (6/6) and
build pass. VERSION 0.7.10 -> 0.7.11. Plan R9 marked done.

web/src/lib/stores/activity.ts

@@ -70,8 +70,8 @@ export const activityLog = derived([messages, planSteps, currentTask], ([$msgs,
     for (const t of $msgs[mi].tools) {
       // Track current step from update_plan_step calls
       if (t.type === 'tool_use' && t.name === 'update_plan_step') {
-        const s = (t.args as any)?.seq as number | undefined
-        const status = (t.args as any)?.status as string | undefined
+        const s = typeof t.args?.seq === 'number' ? t.args.seq : undefined
+        const status = typeof t.args?.status === 'string' ? t.args.status : undefined
         if (s && status === 'running') currentStepSeq = s
       } else if (t.name === 'set_goal' || t.name === 'propose_plan' || t.name === 'complete_task') {
         currentStepSeq = 0
@@ -132,7 +132,7 @@ export const activityLog = derived([messages, planSteps, currentTask], ([$msgs,
   for (let mi = 0; mi < $msgs.length; mi++) {
     for (const t of $msgs[mi].tools) {
       if (t.type === 'tool_result' && t.name === 'upsert_knowledge' && !t.error) {
-        const title = t.args?.title ?? ''
+        const title = typeof t.args?.title === 'string' ? t.args.title : ''
         entries.push({
           id: `knowledge_${mi}`,
           type: 'knowledge',
@@ -172,11 +172,12 @@ export const activityLog = derived([messages, planSteps, currentTask], ([$msgs,
 
 function toolActivityLabel(t: ToolCallResult): string {
   const args = t.args ?? {}
+  const str = (v: unknown): string => typeof v === 'string' ? v : ''
   switch (t.name) {
     case 'set_goal': return 'Set goal'
     case 'propose_plan': return 'Proposed plan'
-    case 'search_knowledge': return `Research: ${args.query || ''}`
-    case 'get_entity': return `Lookup: ${args.slug_or_id || ''}`
+    case 'search_knowledge': return `Research: ${str(args.query)}`
+    case 'get_entity': return `Lookup: ${str(args.slug_or_id)}`
     case 'get_entity_knowledge': return 'Check prior knowledge'
     case 'get_relations': return 'Check relationships'
     case 'list_lxcs': return 'List containers'
@@ -184,8 +185,8 @@ function toolActivityLabel(t: ToolCallResult): string {
     case 'get_health_summary': return 'Fleet health'
     case 'get_state_snapshot': return 'State snapshot'
     case 'run': {
-      const purpose = args.purpose as string || ''
-      const target = (args.target as string) || ''
+      const purpose = str(args.purpose)
+      const target = str(args.target)
       if (purpose) return purpose
       if (target) return `Run on ${target}`
       return 'Run command'