Webapp redesign: fixes from the code review

Blocker
- /reports/export returned 500: REPORT_EXPORT_RANGES and _months_ago were
  deleted with the old reports route. Restored.

Major
- A session without stage_index/stage_total took down /, /imaging and
  /imaging/tiles (int filter on Undefined). The templates default both;
  saving a LAPS password for a session that no longer exists is refused
  (it created a bare session).
- /reports/todo parsed every report four times (23 s at 700 reports).
  blancco_report.parse() now caches by path, mtime and size: 0.09 s.
- Stored XSS through the session serial in the Clear confirm (the
  browser decodes ' before running an inline handler). The message
  moves to data-confirm, and update_session() only accepts serials of
  letters, digits, '.', '_' and '-' (400 from /imaging/status otherwise).
- Reports without a document id and with odd characters in the file name
  got a key the mark routes rejected, so they could never be cleared.
  report_key() now always produces a valid key.

Minor
- failure_note() handles a list-valued erasure target (500 on the report
  and to-do pages).
- _recently_marked() tolerates naive, 'Z' and non-dict state entries.
- Key regexes use fullmatch (a trailing newline was accepted).
- Unreadable reports are no longer counted as to tick / to destroy; the
  reports page already flags them as Unreadable.
- Rollback review recounts restorable files after reading the backups.
- Enrollment: the startnet fallback package (no or empty ppkg.conf) and a
  quoted SOURCE_PPKG are protected too.
- Backup upload overwrite check is case-insensitive (SMB share) and
  replaces the existing file rather than adding a case twin.
- Overview polling keeps the last good rows on an error and pauses while
  the tab is hidden. A shown or typed LAPS password survives the floor's
  refresh.
- hardware_dismiss only redirects to same-site paths; tiles ?limit is
  clamped; the Updates overview survives an unreadable Dell scan or iPXE
  state; describe() uses aversion(); a client cannot label its session
  'inferred'.

webapp/services/blancco_evidence.py

@@ -38,7 +38,11 @@ _REPORT_KEY = re.compile(f"{_DOC_ID.pattern}|{_FILE_KEY.pattern}")
 
 def report_key(document_id: str, filename: str) -> str:
     """The state-file key for one report: its document id, else "file:<name>"."""
-    return document_id if _DOC_ID.match(document_id or "") else f"file:{filename}"
+    if _DOC_ID.fullmatch(document_id or ""):
+        return document_id
+    # Keys travel in URLs and must match _FILE_KEY, so odd characters in a
+    # hand-made report's name ("report (1).xml") become "_".
+    return "file:" + re.sub(r"[^A-Za-z0-9._-]", "_", filename)[:200]
 
 
 # --- state ------------------------------------------------------------------
@@ -68,7 +72,7 @@ def _now() -> str:
 
 
 def record_cloud(document_id: str, sent: bool, serial: str = "", detail: str = ""):
-    if not _DOC_ID.match(document_id or ""):
+    if not _DOC_ID.fullmatch(document_id or ""):
         raise ValueError("bad document_id")
     state = load_state()
     state["cloud"][document_id] = {
@@ -80,7 +84,7 @@ def record_cloud(document_id: str, sent: bool, serial: str = "", detail: str = "
 
 
 def mark_servicenow(document_id: str, done: bool = True):
-    if not _REPORT_KEY.match(document_id or ""):
+    if not _REPORT_KEY.fullmatch(document_id or ""):
         raise ValueError("bad document_id")
     state = load_state()
     if done:
@@ -118,10 +122,11 @@ def collect(since=None, until=None) -> list[dict]:
         path = os.path.join(folder, f)
         if not f.lower().endswith(".xml") or f.startswith(".") or not os.path.isfile(path):
             continue
+        unreadable = False
         try:
             data = blancco_report.parse(path)
         except Exception:
-            data = {}
+            data, unreadable = {}, True
         when = blancco_report.report_datetime(data) or datetime.fromtimestamp(
             os.stat(path).st_mtime, timezone.utc)
         if since and when < since:
@@ -135,6 +140,7 @@ def collect(since=None, until=None) -> list[dict]:
             "when": when,
             "data": data,
             "document_id": (data.get("meta") or {}).get("document_id", ""),
+            "unreadable": unreadable,
         })
         out[-1]["key"] = report_key(out[-1]["document_id"], f)
     return out
@@ -197,6 +203,14 @@ def build_evidence_zip(month: str, fileobj) -> int:
     return len(reports)
 
 
+def _target(er: dict) -> dict:
+    """An erasure's target; parse() makes a repeated target a list."""
+    t = er.get("target") or {}
+    if isinstance(t, list):
+        t = t[0] if t else {}
+    return t if isinstance(t, dict) else {}
+
+
 def failure_note(data: dict):
     """(failed erasures, ServiceNow note) for a parsed report. A drive is
     failed only if none of its erasures succeeded (a Purge failure followed
@@ -210,7 +224,7 @@ def failure_note(data: dict):
         return failed, ""
     reasons = [blancco_report.failure_reason(e) for e in failed]
     drives = ", ".join(
-        f"{(e.get('target') or {}).get('model', '')} {(e.get('target') or {}).get('serial', '')}".strip()
+        f"{_target(e).get('model', '')} {_target(e).get('serial', '')}".strip()
         for e in failed)
     return failed, (f"Blancco wipe failed on {drives or 'drive'}: "
                     f"{'; '.join(x.rstrip('. ') for x in reasons if x) or 'no erasure recorded'}. "
@@ -223,6 +237,8 @@ def servicenow_items(days: int = 30, include_done: bool = False) -> list[dict]:
     state = load_state()
     items = []
     for r in reversed(collect(since)):
+        if r.get("unreadable"):
+            continue  # /reports flags it as Unreadable; nothing to tick or destroy
         done = state["servicenow"].get(r["key"])
         if done and not include_done:
             continue
@@ -260,7 +276,7 @@ _EVIDENCE_ZIP = re.compile(r"^ENT-056_.+_(20\d\d-\d\d)\.zip$")
 
 def mark(kind: str, key: str, done: bool = True):
     pattern = TODO_KINDS.get(kind)
-    if not pattern or not pattern.match(key or ""):
+    if not pattern or not pattern.fullmatch(key or ""):
         raise ValueError("bad to-do item")
     state = load_state()
     bucket = state.setdefault(kind, {})