fix(remote): stop the wake handlers shadowing each other; enforce the input cap

Two findings from a final review pass over the wake-on-LAN feature.

`_onRemoteHostWaking` / `_onRemoteHostWakeFailed` were defined in BOTH
`panels-ui.js` (toasts) and `host-wake-ui.js` (banner). Both files mix into
`CodemanApp.prototype` and `host-wake-ui.js` loads later, so the panels-ui copies
were silently shadowed: the toast never fired, and a wake started for a BACKGROUND
session (input on a non-active tab) produced no notification at all, since the
banner handler only acts on the active session. The handlers now live only in
`host-wake-ui.js`, show the toast unconditionally, and update the banner when the
woken session is the active one.

`appendBoundedPending` dropped only WHOLE chunks, so a single input value over the
cap (one large paste is one `input` value, up to the 100 KB input schema) was kept
in full: "bounded at 4 KB" held per chunk, not per session, and nothing was logged.
The surviving chunk's head is now trimmed too, code-point aware so a multi-byte
character is never split into a replacement char.

Adds the guard that would have caught the first one: every SSE dispatch handler must
be defined in exactly ONE frontend module. The existing test only asserts a handler
EXISTS somewhere, which two modules both satisfy while one is shadowed.

test/sse-dispatch-table.test.ts

@@ -57,4 +57,22 @@ describe('SSE dispatch table', () => {
       .filter((handler) => !new RegExp(`(^|\\s)${handler}\\s*\\(`, 'm').test(allModules));
     expect(missing).toEqual([]);
   });
+
+  it('defines every handler in exactly ONE module (a second copy is shadowed)', () => {
+    // Modules mix into `CodemanApp.prototype` and run in script order, so two
+    // definitions of the same handler name silently shadow each other: the later file
+    // wins and the earlier one never runs. The existence check above cannot see that
+    // (both names resolve), which is how a duplicate banner handler can leave a toast
+    // dead with no error anywhere.
+    const byModule = readdirSync(PUBLIC_DIR)
+      .filter((name) => name.endsWith('.js'))
+      .map((name) => ({ name, source: readFileSync(join(PUBLIC_DIR, name), 'utf-8') }));
+    const shadowed = dispatchEntries()
+      .map((entry) => entry.handler)
+      .filter((handler) => {
+        const re = new RegExp(`(^|\\s)${handler}\\s*\\(`, 'm');
+        return byModule.filter((mod) => re.test(mod.source)).length > 1;
+      });
+    expect(shadowed).toEqual([]);
+  });
 });