fix(#585): render terminal tool output via real backend payload keys (#595)

The backend terminal tool (tools/terminal_tool.py) returns a single merged
'output' string plus 'exit_code' and 'error' — never 'stdout'/'stderr'.
ChatBubble was reading the non-existent 'stdout' key, so command output was
silently dropped and only the Duration footer showed.

- Parse 'output' as canonical; keep legacy 'stdout'/'stderr' fallback for
  backward compat.
- Route terminal output into mainOutput so it renders like other tool bubbles.
- Surface non-zero exit codes as an error line when no 'error' string is set.
- Remove dead 'stderr' render branch.
- Update ToolBubbleParsingTest to assert the real payload shape (incl. the
  exact issue-585 'echo hellp' sample) and add regression cases.

Co-authored-by: hy4ri <hy4ri@users.noreply.github.com>

app/src/test/java/com/m57/hermescontrol/ui/chat/ToolBubbleParsingTest.kt

@@ -11,25 +11,65 @@ class ToolBubbleParsingTest {
     // ── Terminal ──────────────────────────────────────────────
 
     @Test
-    fun testParseTerminal_withStdout() {
+    fun testParseTerminal_withOutput() {
         val json =
             """{
             "tool_id": "call_001",
             "name": "terminal",
+            "args": {"command": "echo hellp"},
+            "result": {"output": "hellp", "exit_code": 0, "error": null},
+            "duration_s": 0.06
+        }"""
+        val parsed = parseToolOutput(json, "terminal", false)
+        assertNotNull(parsed)
+        assertEquals("terminal", parsed!!.toolName)
+        assertTrue(parsed.isTerminal)
+        assertEquals("hellp", parsed.stdout)
+        assertEquals("hellp", parsed.mainOutput)
+        assertEquals(0, parsed.exitCode)
+        assertEquals(0.06, parsed.durationSec!!, 0.01)
+        assertEquals("$ echo hellp", parsed.summaryText)
+    }
+
+    @Test
+    fun testParseTerminal_legacyStdout() {
+        val json =
+            """{
+            "tool_id": "call_001b",
+            "name": "terminal",
             "args": {"command": "npm run build"},
             "result": {"stdout": "Build succeeded!", "exit_code": 0},
             "duration_s": 5.2
         }"""
         val parsed = parseToolOutput(json, "terminal", false)
         assertNotNull(parsed)
-        assertEquals("terminal", parsed!!.toolName)
-        assertTrue(parsed.isTerminal)
+        assertTrue(parsed!!.isTerminal)
         assertEquals("Build succeeded!", parsed.stdout)
+        assertEquals("Build succeeded!", parsed.mainOutput)
         assertEquals(0, parsed.exitCode)
         assertEquals(5.2, parsed.durationSec!!, 0.01)
         assertEquals("$ npm run build", parsed.summaryText)
     }
 
+    @Test
+    fun testParseTerminal_floatExitCode_isNotDropped() {
+        // Backend emits exit_code as a FLOAT (0.0), not an int. asInt on a
+        // "0.0" primitive throws NumberFormatException, which previously
+        // nulled the whole parse -> raw JSON. Reproduces the live bug.
+        val json =
+            """{
+            "tool_id": "call_001d",
+            "name": "terminal",
+            "args": {"command": "echo hi"},
+            "result": {"output": "hi", "exit_code": 0.0, "error": null}
+        }"""
+        val parsed = parseToolOutput(json, "terminal", false)
+        assertNotNull("float exit_code must not null the parse", parsed)
+        assertTrue(parsed!!.isTerminal)
+        assertEquals("hi", parsed.stdout)
+        assertEquals(0, parsed.exitCode)
+    }
+
     @Test
     fun testParseTerminal_withStderr() {
         val json =
@@ -42,7 +82,7 @@ class ToolBubbleParsingTest {
         val parsed = parseToolOutput(json, "terminal", false)
         assertNotNull(parsed)
         assertTrue(parsed!!.isTerminal)
-        assertEquals("Permission denied", parsed.stderr)
+        assertEquals("Permission denied", parsed.stdout)
         assertEquals(1, parsed.exitCode)
         assertEquals("$ rm -rf /", parsed.summaryText)
     }