Add search and filter to the guest table

/ opens a filter box under the guest table, and the table filters as
you type. Terms are separated by spaces, all must match, and case is
ignored:

- a plain term matches part of the name, the VMID or a tag
- is:running and is:stopped match the status
- type:lxc/ct and type:vm/qemu match the guest type

Enter keeps the filter and goes back to the table. Escape clears it,
from the box or from the table. The frame shows
"· filter: <text> · N of M". Actions only ever see the visible rows,
and the filter survives reloads and context switches.

Review fixes:
- Typing "[/b]" or "[/]" crashed the app, because the filter text went
  into the border subtitle, which Textual parses as markup. The
  subtitle is now plain text, so "[red]" is also shown literally.
- Escape on the table now clears a filter that was applied with Enter.
- guest_matches tolerates a None status or type.

Read-only live check on mainframe: "debian" gives 104, "type:vm" gives
108, "community-script is:running" gives 14 of 19, and "is:stopped"
gives 0 of 19.

Closes #16

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/cv4pve_tui/app.py

@@ -23,6 +23,7 @@ from textual.widgets import (
     Select,
     Static,
 )
+from textual.widgets._data_table import RowDoesNotExist
 from textual.widgets.option_list import Option
 
 from cv4pve_tui import cli
@@ -991,12 +992,45 @@ def _job_text(job: dict) -> str:
     )
 
 
+_TYPES = {"lxc": "lxc", "ct": "lxc", "vm": "qemu", "qemu": "qemu"}
+
+
+def guest_matches(guest: dict, query: str) -> bool:
+    """True if the guest matches every space-separated term (case-insensitive).
+
+    Plain term: substring of the name, the VMID or one tag. `is:running|stopped`
+    matches the status, `type:lxc|ct|vm|qemu` the type; an unknown value matches nothing.
+    """
+    tags = (guest.get("tags") or "").lower().split(";")
+    for term in query.lower().split():
+        key, _, value = term.partition(":")
+        if key == "is" and value:
+            ok = (guest.get("status") or "").lower() == value
+        elif key == "type" and value:
+            ok = _TYPES.get(value) == (guest.get("type") or "").lower()
+        else:
+            ok = (
+                term in str(guest.get("name", "")).lower()
+                or term in str(guest.get("vmid", ""))
+                or any(term in t for t in tags)
+            )
+        if not ok:
+            return False
+    return True
+
+
 class GuestTable(DataTable):
     """The guest table; shows its Enter (row selected -> info screen) in the footer."""
 
     BINDINGS = [Binding("enter", "select_cursor", "Info")]  # noqa: RUF012 - Textual idiom
 
 
+class FilterInput(Input):
+    """The filter box; Escape clears and hides it."""
+
+    BINDINGS = [Binding("escape", "app.clear_filter", "Clear filter")]  # noqa: RUF012 - Textual idiom
+
+
 class GuestApp(App):
     BINDINGS = [  # noqa: RUF012 - Textual idiom
         ("s", "act('start')", "Start"),
@@ -1006,9 +1040,12 @@ class GuestApp(App):
         ("t", "shell", "Shell"),
         ("g", "reload", "Refresh"),
         ("c", "context", "Context"),
+        ("slash", "filter", "Filter"),
         ("l", "tasks", "Tasks"),
         ("U", "updates", "Updates"),
         ("q", "quit", "Quit"),
+        # also on the table, once a filter was applied with Enter (focus left the input)
+        Binding("escape", "clear_filter", "Clear filter", show=False),
     ]
 
     def __init__(self) -> None:
@@ -1028,6 +1065,7 @@ class GuestApp(App):
         border: round $accent; border-title-style: bold; padding: 0 1;
     }
     #guests_section DataTable { height: 1fr; }
+    #filter { display: none; }
     """
 
     def compose(self) -> ComposeResult:
@@ -1035,6 +1073,9 @@ class GuestApp(App):
         with Vertical(id="guests_section") as section:
             section.border_title = "Guests"
             yield GuestTable(id="guests", cursor_type="row")
+            yield FilterInput(
+                id="filter", placeholder="name, vmid, tag · is:running · type:lxc"
+            )
         yield Footer()
 
     def on_mount(self) -> None:
@@ -1111,10 +1152,17 @@ class GuestApp(App):
     def _update_frame(self) -> None:
         n = len(self.unprotected & {g["vmid"] for g in self.guests.values()})
         count = f" · {n} without backup job" if n else ""
+        query = self.query_one("#filter", Input).value.strip()
+        if query:
+            shown = self.query_one("#guests", DataTable).row_count
+            count = f" · filter: {query} · {shown} of {len(self.guests)}" + count
         if self.package_count:
             n = self.package_count
             count += f" · {n} package update{'s' if n != 1 else ''}"
-        self.query_one("#guests_section").border_subtitle = self.context_name + count
+        # plain text: the filter is typed by the user and must never be parsed as markup
+        self.query_one("#guests_section").border_subtitle = Text(
+            self.context_name + count
+        )
 
     @work(thread=True)
     def _show_context(self) -> None:
@@ -1150,11 +1198,22 @@ class GuestApp(App):
         if gen != self.generation:  # listed before a context switch: old cluster
             return
         self.unprotected = unprotected or set()
-        table = self.query_one("#guests", DataTable)
-        current = self._selected()
-        table.clear()
         self.guests = {str(g["vmid"]): g for g in guests}
-        for g in guests:
+        self._show_guests()
+
+    def _show_guests(self) -> None:
+        """Rebuild the table from self.guests: only the guests matching the filter."""
+        table = self.query_one("#guests", DataTable)
+        current = (  # the key, not _selected(): self.guests may already be the new listing
+            table.coordinate_to_cell_key(table.cursor_coordinate).row_key.value
+            if table.row_count
+            else None
+        )
+        table.clear()
+        query = self.query_one("#filter", Input).value
+        for g in self.guests.values():
+            if not guest_matches(g, query):
+                continue
             _add_plain(table,
                 "!" if g["vmid"] in self.unprotected else "",
                 g["vmid"], g["name"], g["type"], g["node"], g["status"],
@@ -1162,10 +1221,32 @@ class GuestApp(App):
                 *_percents(g),
                 key=str(g["vmid"]),
             )  # fmt: skip
-        if current and str(current["vmid"]) in self.guests:
-            table.move_cursor(row=table.get_row_index(str(current["vmid"])))
+        if current is not None:
+            try:
+                table.move_cursor(row=table.get_row_index(current))
+            except RowDoesNotExist:  # gone or filtered out: keep the default cursor
+                pass
         self._update_frame()
 
+    def action_filter(self) -> None:
+        box = self.query_one("#filter", Input)
+        box.display = True
+        box.focus()
+
+    def action_clear_filter(self) -> None:
+        box = self.query_one("#filter", Input)
+        box.value = ""  # Input.Changed rebuilds the table
+        box.display = False
+        self.query_one("#guests", DataTable).focus()
+
+    def on_input_changed(self, event: Input.Changed) -> None:
+        if event.input.id == "filter":
+            self._show_guests()
+
+    def on_input_submitted(self, event: Input.Submitted) -> None:
+        if event.input.id == "filter":
+            self.query_one("#guests", DataTable).focus()
+
     def _reload(self, acted: dict | None = None) -> None:
         """Runs in a worker thread. `acted` gets its live status: the listing lags."""
         gen = self.generation