Bugfixed by Claude

[tropotek]

v5.2 - connection setup bugfixes (Mick Mifsud)

• Flaky first-time connection setup. RepetierOutputDevicePlugin decided whether to push
  the API key into a live connection by comparing the Repetier server instance's own name
  against Cura's auto-generated machine container id — two unrelated values that only matched
  by coincidence. This is why setup required repeatedly deleting/re-adding the printer profile.
  Fixed by persisting an explicit repetier_instance_id link on the machine when "Connect" is
  clicked, and matching on that. Existing (accidentally-working) profiles are migrated
  automatically on first reconnect (legacy id-match still honored as a fallback, then
  self-heals by backfilling the new metadata).
• API key never validating on new profiles, leaving "Connect" permanently disabled. The
  wizard's "RepetierID" and "API Key" fields were reading Cura container metadata keyed by the
  Repetier server instance's name instead of the active machine's id — essentially never a
  valid lookup for a fresh profile. Fixed to read the printer slug directly off the selected
  instance and the API key from the active machine.
• Same root-cause bug (server-instance identity vs. machine id) was also present in the
  instance-list "linked instance" bolding (font.italic was comparing against a nonexistent
  .key property and the wrong metadata field) and in the "Edit" button's pre-fill logic for
  the manual-instance dialog. Both fixed to use the same reliable source.
• "Get Printers" button required multiple clicks, and appeared to "cache" against the IP.
  getPrinterList() fires an async network request but the QML read the result synchronously
  right after calling it — always one click behind. Added a printersChanged signal (properly
  notified when the response actually lands) and an isFetchingPrinters busy flag; the button
  now disables while in flight and the dropdown populates reliably on the first response.
  Re-fetching now also preserves the current selection if it's still present in the new list.
• UnboundLocalError crash silently breaking printer status polling whenever a stateList
  response omitted numExtruder (seen with a real printer profile) — printer_state was only
  assigned inside a conditional branch but used unconditionally afterward. The except: handler
  for this case then also crashed on printer.activePrintJob being None. Both fixed.
• A second, identical AttributeError landmine in the listPrinter response handler
  (self._key was never defined anywhere — should have been self._repetier_id).
• "Store G-code on the printer SD card" checkbox silently did nothing — the setting was
  read back with a case-mismatched metadata key (Repetier_store_sd vs. the stored
  repetier_store_sd), so it always evaluated to the default (off).
  Fixed to use the matching, correctly-cased key.
• Unguarded location_url dereference in the upload-finished handler — would crash if Repetier
  ever omits the Location header on a successful auto-print upload. Added a guard with a
  clear error message instead.
• Missing QSslConfiguration/QSslSocket imports and PyQt6 enum-scoping issues
  (FollowRedirectsAttribute, VerifyNone) in DiscoverRepetierAction._createRequest() —
  currently unreachable dead code (not wired to any UI button) but would have crashed
  immediately if ever invoked.
• Duplicate connectionStateChanged signal connections stacking up on every reconnect attempt,
  causing repeated/duplicated addOutputDevice/removeOutputDevice calls during setup. Now
  disconnects before reconnecting.
• RepetierOutputDevice.connect() had no idempotency guard, so rapid successive calls (e.g.
  from setInstanceId() and setApiKey() each triggering a reconnect) restarted the poll timer
  and re-issued a burst of duplicate HTTP requests. Now a no-op while already
  connecting/connected.
• Invalid API key (HTTP 401) left the connection silently stuck in "Connecting" with no visible
  error state. Now surfaces a proper Error state and recovers to Connected automatically on
  the next successful poll once the key is corrected.

Changed

• Instance list now bolds (moderate weight, not full bold) the Repetier instance currently
  linked to the active printer, and shows a "currently linked" label when it's selected.
• "Connect" is disabled while viewing the already-linked instance and enables as soon as a
  different instance is selected.
• Group dropdown ("Store print job and print") now renders Repetier-Server's # (default/
  ungrouped bucket) as "(Default)" instead of the raw symbol, and defaults to the first
  available group instead of leaving no selection.
• manualPrinterDialog.onAccepted no longer writes repetier_id metadata onto whichever
  machine happens to be active just from adding/editing a server entry in the list — that link
  is only ever made via the explicit "Connect" action now.

Removed

• Dead code: NetworkReplyTimeout.py (never instantiated) and all references to it.
• config.jpg, webcam.jpg, and Cura 4.1 testing doc.rtf.zip — stale screenshots/testing doc
  from the Cura 4.1 era, superseded by the current README instructions.
• README's "must match the Instance Name" workaround note — no longer applicable now that
  linking is explicit rather than name-coincidence-based.