Fix K-profile greenlet error on auto-created RFID spools

  create_spool_from_tray() didn't eagerly load the k_profiles
  relationship, so auto_assign_spool() triggered a lazy load in async
  context when iterating spool.k_profiles. Set k_profiles=[] on new
  spools since they can never have K-profiles yet.

CHANGELOG.md

@@ -21,6 +21,7 @@ All notable changes to Bambuddy will be documented in this file.
 - **Inventory Scale Weight Check Column** — Added a "Weight Check" column (hidden by default) to the inventory table that compares each spool's last scale measurement against its calculated gross weight (net remaining + core weight). Spools within a ±50g tolerance show a green checkmark; mismatched spools show a yellow warning with the difference and a sync button that trusts the scale reading and resets weight tracking. The backend stores `last_scale_weight` and `last_weighed_at` on each spool whenever weight is synced via SpoolBuddy, and the column tooltip shows scale weight, calculated weight, and difference. Edge case: when scale weight is below core weight (empty spool or not on scale), the comparison treats it as a match since sync can't correct this.
 
 ### Fixed
+- **K-Profile Apply Fails With Greenlet Error on Auto-Created Spools** — When a Bambu Lab spool was detected via RFID for the first time (auto-creating a new inventory entry), the K-profile application step logged `WARNING greenlet_spawn has not been called; can't call await_only() here`. The `create_spool_from_tray()` function flushed the new spool to the database but didn't eagerly load the `k_profiles` relationship. When `auto_assign_spool()` then iterated `spool.k_profiles` to find a matching K-profile, SQLAlchemy attempted a lazy load — which requires a synchronous DB call that's illegal inside an async context. The K-profile step was silently skipped (caught by `except Exception`), so spool assignment still worked but without K-profile selection. Now eagerly sets `k_profiles = []` on newly created spools since they can never have K-profiles yet.
 - **SpoolBuddy Link Tag Missing tag_type** — Linking an NFC tag to a spool via the SpoolBuddy dashboard's "Link to Spool" action only set `tag_uid` but left `tag_type` and `data_origin` empty, because it called the generic `updateSpool` API instead of the dedicated `linkTagToSpool` endpoint. The printer card's `LinkSpoolModal` already used `linkTagToSpool` correctly. Now uses `linkTagToSpool` with `tag_type: 'generic'` and `data_origin: 'nfc_link'`, which also handles conflict checks and archived tag recycling.
 - **SpoolBuddy AMS Page Missing Fill Levels for Non-BL Spools** — AMS slots with non-Bambu Lab spools assigned to inventory didn't show fill level bars on the SpoolBuddy AMS page, even though the main printer card displayed them correctly. The SpoolBuddy AMS page only used the MQTT `remain` field (which is -1/unknown for non-BL spools), while the printer card had a fallback chain: Spoolman → inventory → AMS remain. Now fetches inventory spool assignments and computes fill levels from `(label_weight - weight_used) / label_weight`, falling back to AMS remain when no inventory assignment exists.
 - **SpoolBuddy AMS Page Ext-R Slot Falsely Shown as Active When Idle** — On dual-nozzle printers (H2D), the Ext-R slot was incorrectly highlighted as active when the printer was idle. The ext-R tray has `id=255`, and the idle sentinel `tray_now=255` matched it via `trayNow === extTrayId`. The main printer card avoided this by clearing `effectiveTrayNow` to `undefined` when `tray_now=255`. Now guards against `tray_now=255` before any ext slot active check.

backend/app/services/spool_tag_matcher.py

@@ -145,6 +145,10 @@ async def create_spool_from_tray(db: AsyncSession, tray_data: dict) -> Spool:
     db.add(spool)
     await db.flush()
 
+    # Eagerly set k_profiles so callers (auto_assign_spool) don't trigger
+    # a lazy load in async context (greenlet_spawn error).
+    spool.k_profiles = []
+
     logger.info(
         "Auto-created spool %d from AMS tray data: %s %s %s (tag=%s uuid=%s)",
         spool.id,