Projection Mapper Native 0.86.0 - snapshots, title colors, nav icons, tag filters, person-gated scares

NEW IN 0.86.0
Five additions in one release:
1. Show snapshot button (Show page, Playback card): saves the exact frame on
   the projector right now as a JPEG into the guestbook folder, named
   snapshot-<date-time>.jpg. Handy for "keep that one" moments and for
   showing Wade what the house looks like mid-show.
2. Title colors (Timeline page): per-scene dropdown next to the title text -
   warm white (the existing look), amber, green, red, blue, or violet. Applies
   to both lines of two-line titles and works with the animated title cards.
3. Nav icons: every left-nav entry now has a small hand-drawn icon (pure GDI,
   no image files, no downloads). Active page icon uses the accent color.
4. Tag filters (Content library): the search row is now text box + tag
   dropdown. Tags come from the web app's tags.json (both known shapes read)
   plus built-in prefix tags: hw-/hw2- packs, guestbook-, snapshot-. Filtering
   combines with the text search.
5. Motion-gated person detection (Automation page): a scare dropdown with
   three modes -
     - Scare on any motion (the existing behavior, and the default)
     - Scare on a person - motion fallback until the detector is ready
     - Scare only when the detector sees a person
   plus a "Set up person detection" button. The detector is a small local
   python sidecar that reuses the Detection AI venv from the Detect page
   setup (ultralytics is already installed there - no second big download)
   and a yolo11n model (~6 MB, fetched once by the ultralytics library itself
   on first use; runs on the RTX 2060). Motion fires the detector, a person
   box at confidence 0.45+ gates the scare, and in fallback mode a detector
   that is down, warming, or erroring never silently kills the scare. Every
   motion event logs the detector verdict ("person 0.63", "no person seen",
   "motion-only (detector not ready)") next to the guestbook moment.

STILL TRUE
- Windows 10/11 64-bit. No install: run the exe, it lives in %APPDATA%\ProjectionMapperNative.
- Auto-update and the automatic log file work as before.
- Safe mode reduces procedural effect speed/intensity within tested bounds - it is not a guarantee.
- Control socket: localhost-only, token required, never logged, fail-closed. The
  detector sidecar is localhost-only too and only accepts camera frames.

TESTED (build machine)
- Full Go test suite passes, including the new gate tests: fallback mode scares
  when the detector is down and stays quiet when it sees no person; strict mode
  requires a person; sidecar JSON parsing (multiple boxes, below-threshold,
  error replies, garbage); detector labels.
- Title color, tag parsing (both tags.json shapes), prefix tags, library
  tag filtering, snapshot naming: unit tested.
- Windows cross-build (GOOS=windows) green; go vet clean.

UNTESTED (needs Wade's rig)
- The detector sidecar end to end: venv detection, script write, model
  download, GPU inference time, and the live scare gating. The python and the
  model cannot run in the build environment. Default gate mode is OFF, so the
  scare behaves exactly as 0.85.1 until a person mode is picked; if setup
  fails, fallback mode still scares on motion.
- Nav icon rendering and the new Automation/library/Show layouts on the real
  773px window.
- Tag dropdown against a live web-app tags.json (unit tested on both
  documented shapes only).

JUDGMENT CALLS
- Gate defaults OFF: nobody's scare changes unless they pick a person mode.
- Setup reuses the existing Detection AI venv instead of a second install;
  if neither venv exists the button says to run Detect-page setup first.
- ultralytics licensing: it is pip-installed on Wade's own machine by his
  earlier Detect-page setup action and the model file downloads at runtime -
  nothing ultralytics ships inside this exe or the source zip.
- Person threshold 0.45 (the middle of the scouted 0.4-0.5 band).
- The scare check runs on the Automation tick (every 20 s), same cadence as
  the existing motion check - the gate adds no new polling.
- Snapshots land in the guestbook folder so the slideshow page can show them;
  the snapshot- prefix tag keeps them filterable.

Gemini calls this build: 0.