fix(suggestion): stop generating mid-typing and let a pause bring a suggestion at once

With a 100 ms trigger left in the installed config, generation started in the
gaps between keystrokes; the next key ended the session silently, and that
session still counted against the 5 s minimum interval, so the moment the
user actually paused nothing came (rate-limited). The log showed a
generate-then-vanish cycle every 5-6 s.

The trigger delay now has a 500 ms floor and settings revision 6 resets a
stored value below it to 600 ms. A session ended because the user kept typing
no longer blocks the next request by the minimum interval (per-minute and
daily caps still apply), and that dismissal is logged.

apps/desktop/tests/main/services/ConfigService.test.ts

@@ -48,7 +48,7 @@ describe('ConfigService suggestion tuning migration', () => {
     )
     await initConfigService()
 
-    expect(configGet('suggestionTuningRevision')).toBe(5)
+    expect(configGet('suggestionTuningRevision')).toBe(6)
     expect(configGet('suggestionTriggerDelayMs')).toBe(600)
     expect(configGet('suggestionMaxRequestsPerMinute')).toBe(6)
     expect(configGet('suggestionMinPrefixChars')).toBe(17)
@@ -114,7 +114,7 @@ describe('ConfigService suggestion tuning migration', () => {
     // 옮기지 않는 액션은 그대로 남는다.
     expect(bindings['suggestion-next']).toEqual(OLD_NEXT)
     expect(bindings['suggestion-prev']).toEqual(OLD_PREV)
-    expect(configGet('suggestionTuningRevision')).toBe(5)
+    expect(configGet('suggestionTuningRevision')).toBe(6)
 
     resetInMemoryConfig()
   })
@@ -144,4 +144,43 @@ describe('ConfigService suggestion tuning migration', () => {
     resetInMemoryConfig()
   })
 
+  it('revision 6: 하한(500ms) 미만으로 남은 멈춤 판단 시간만 기본값 600ms로 되돌린다', async () => {
+    for (const [stored, expected] of [
+      [100, 600],
+      [800, 800],
+    ] as const) {
+      const persisted = { suggestionTuningRevision: 5, suggestionTriggerDelayMs: stored }
+
+      class TestStore<T extends Record<string, unknown>> {
+        store: T
+
+        constructor(options: { defaults: T }) {
+          this.store = { ...options.defaults, ...persisted } as T
+        }
+
+        get<K extends keyof T>(key: K): T[K] {
+          return this.store[key]
+        }
+
+        set<K extends keyof T>(key: K, value: T[K]): void {
+          this.store[key] = value
+        }
+
+        delete(key: string): void {
+          delete this.store[key as keyof T]
+        }
+      }
+
+      vi.doMock('electron-store', () => ({ default: TestStore }))
+      const { configGet, initConfigService, resetInMemoryConfig } = await import(
+        '../../../src/main/services/ConfigService'
+      )
+      await initConfigService()
+      expect(configGet('suggestionTuningRevision')).toBe(6)
+      expect(configGet('suggestionTriggerDelayMs')).toBe(expected)
+      resetInMemoryConfig()
+      vi.doUnmock('electron-store')
+      vi.resetModules()
+    }
+  })
 })