[no bump] Implement telegra.ph media forward

Adds a share action to the Instant View photo viewer that downloads the
media and re-sends it from the user's own account with a text_url caption
linking back to the source article.

- src/main.py: hooks PhotoViewer.onPhotoShow, injects the toolbar item
- src/ivmedia.py: resolves the viewer's page block to a TL media object
- src/picker.py: share sheet + comment field (restores focus after the
  keyboard animation, which PhotoViewer.showShareAlert does itself)
- src/sender.py: FileLoader download, cache reuse, re-send with caption
- src/icons.py: IconManager-aware drawable lookup so icon packs apply
- tools/verify_bundle.py: offline checks for URL acceptance, caption
  entity shape and bundled-module isolation

Drops the sample greeting/textutil modules.

src/picker.py

@@ -0,0 +1,92 @@
+"""Opens the client's own "Share / Forward to" sheet and reports the chosen chats.
+
+`ShareAlert` is the sheet the app itself uses for forwarding, so reusing it keeps
+the picker pixel-identical to the stock one. It is constructed with no payload
+(`sendingMessageObjects`, `sendingText` and `sendingFile` all null), which makes
+its send path a no-op: it selects chats, fires `ShareAlertDelegate.didShare()`
+and dismisses. The selection is read back off the (protected) `selectedDialogs`
+field and the comment off `commentTextView`.
+"""
+
+from android_utils import log, run_on_ui_thread
+from hook_utils import get_private_field
+
+_delegate_class = None
+
+# ShareAlert's own constant for "keep the keyboard out of the way".
+_SOFT_INPUT_ADJUST_NOTHING = 48
+
+# PhotoViewer hands focus over after AdjustPanLayoutHelper.keyboardDuration,
+# which is 250ms in the app's animation constants.
+_FOCUS_DELAY_MS = 250
+
+
+def _make_delegate_class():
+    """Builds the ShareAlertDelegate proxy lazily: the Java interface can only
+    be resolved once the app classes are loadable."""
+    from java import dynamic_proxy
+    from org.telegram.ui.Components import ShareAlert
+
+    class Delegate(dynamic_proxy(ShareAlert.ShareAlertDelegate)):
+        def __init__(self, alert, on_picked):
+            super().__init__()
+            self.alert = alert
+            self.on_picked = on_picked
+
+        def didCopy(self):
+            return False
+
+        def didShare(self):
+            self.on_picked(_selected_peers(self.alert), _comment(self.alert))
+
+    return Delegate
+
+
+def _selected_peers(alert):
+    dialogs = get_private_field(alert, "selectedDialogs")
+    if dialogs is None:
+        return []
+    return [dialogs.keyAt(i) for i in range(dialogs.size())]
+
+
+def _comment(alert):
+    field = get_private_field(alert, "commentTextView")
+    if field is None:
+        return ""
+    text = field.getText()
+    return str(text).strip() if text is not None else ""
+
+
+def pick_chats(context, on_picked, resources_provider=None):
+    """Shows the stock share sheet. `on_picked(dialog_ids, comment)` runs on the
+    UI thread once the user confirms."""
+    global _delegate_class
+    from org.telegram.ui.Components import ShareAlert
+
+    alert = ShareAlert(context, None, None, False, None, False, resources_provider)
+
+    if _delegate_class is None:
+        _delegate_class = _make_delegate_class()
+    # Keep a reference on the module so the proxy is not collected early.
+    delegate = _delegate_class(alert, on_picked)
+    alert.setDelegate(delegate)
+    pick_chats._alive = delegate
+
+    # ShareAlert opens over PhotoViewer's window. Taking focus immediately
+    # fights the viewer's own window animation, so the stock code in
+    # PhotoViewer.showShareAlert() starts unfocused and hands focus over once
+    # the keyboard-transition window has passed; without that second step the
+    # comment field can be tapped but never receives key events.
+    alert.setFocusable(False)
+    alert.getWindow().setSoftInputMode(_SOFT_INPUT_ADJUST_NOTHING)
+    run_on_ui_thread(lambda: _enable_focus(alert), _FOCUS_DELAY_MS)
+    alert.show()
+    return alert
+
+
+def _enable_focus(alert):
+    try:
+        if alert.getWindow() is not None:
+            alert.setFocusable(True)
+    except Exception as exc:
+        log("[telegraph_media_forward] focus handoff failed: %s" % exc)