Add Panasonic Lumix BLE camera support

[MaxRink]

Motivation

Panasonic Lumix cameras are the highest-ranked missing vendor in plan 61.
Adding them broadens furble camera coverage so Lumix owners get the same
native BLE shutter, focus, and GPS sidecar support the other vendors already
have.

What changed

• New Furble::Lumix vendor class (lib/furble/Lumix.h / Lumix.cpp), one
  class per vendor mode, ported from upstream PR 282 onto the fork vendor API.
• Camera::Type::PANASONIC_LUMIX added as enum value 10 (NVS-persisted type
  id, never renumbered).
• CameraList registers the saved-camera load path and the scan match()
  path.
• Implements the MEI0 session-init handshake seen in S5II and BGH1 HCI traces,
  the device-name identity write, single-byte shutter/focus commands, and the
  GPS location plus clock sidecar writes. The GPS-epoch conversion is kept
  local since the fork has no Camera::toUnixTime() helper.
• Docs: lib/furble/CLAUDE.md, plans/72-lumix.md, plans/61 implementation
  state, and plans/README.md index updated.

Wire ids

• Camera type id: PANASONIC_LUMIX = 10 (NVS-persisted). No new settings wire
  id is used; the settings ledger next-free stays 41. Provisional ids may be
  renumbered at integration if sibling vendor branches collide.

Verification

• M5StickS3 release firmware build: SUCCESS
  (FURBLE_VERSION=dev FURBLE_TEST=0 pio run -e m5stick-s3).
• SDL simulator build: sim/build.sh SUCCESS. No sim shim was needed; the sim
  uses the shim/CameraList.h fake and does not compile the real registry.
• clang-format 21 clean, no em-dashes, no conflict markers.

UNTESTED on hardware

No Panasonic Lumix camera is available in this workspace. This change is
validated only by code review, the S3 compile, and the FauxNY/simulator path.
It has not been exercised against a real Lumix camera. The S5II first-pair path
may still need the camera-side WiFi-assisted Lumix Sync handshake, and the
G9II-generation XOR login is not implemented.

🤖 Generated with Claude Code

Data sources

• Upstream furble Lumix PR: Add support for Panasonic LUMIX cameras gkoh/furble#282
• LUMIX lat/long log protocol notes: https://github.com/tobiasbrummer/lux-lat-long-log
• LUMIX G9II remote control reference: https://github.com/Aikhjarto/LUMIX-G9II-Remote-Control

Untested on Panasonic hardware; code review + FauxNY only.

Upstream issues

Addresses gkoh#247.

[github-actions]

Firmware size report

Env	Flash used	RAM used	Flash delta vs base	RAM delta vs base
m5stack-core	1,189,784 B (68.3%)	41,248 B	+4,100 B (+0.35%)	+176 B ⚠️
m5stack-core-debug	1,400,441 B (80.4%)	42,412 B	+4,504 B (+0.32%)	+184 B ⚠️
m5stack-core2	1,189,888 B (68.4%)	41,256 B	+4,108 B (+0.35%)	+176 B ⚠️
m5stack-core2-debug	1,400,553 B (80.5%)	42,412 B	+4,500 B (+0.32%)	+184 B ⚠️
m5stick-c	1,125,500 B (64.7%)	41,256 B	+4,100 B (+0.37%)	+176 B ⚠️
m5stick-c-debug	1,349,857 B (77.5%)	42,396 B	+4,516 B (+0.34%)	+184 B ⚠️
m5stick-c-plus	1,142,152 B (65.6%)	41,256 B	+4,092 B (+0.36%)	+176 B ⚠️
m5stick-c-plus-debug	1,352,861 B (77.7%)	42,396 B	+4,524 B (+0.34%)	+184 B ⚠️
m5stick-s3	1,219,320 B (70.0%)	34,548 B	+4,160 B (+0.34%)	+176 B ⚠️
m5stick-s3-debug	1,446,905 B (83.1%)	35,820 B	+4,444 B (+0.31%)	+184 B ⚠️

Base comparison: latest master build at commit 0c310719919b.
Flash growth over 1% and any positive RAM delta are marked with ⚠️.