perf: generate the crossing animation instead of storing 2 KB of bitmaps (backport of #119)

[TheAngryRaven]

Backport of b16c42e (#119) from the beta channel to master — 2,048 B of flash, isolated code, already proven on beta.

What

The two "calculating" frames shown while inside a crossing zone were hand-stored 1 KB PROGMEM bitmaps. Decoding them shows both are pure block patterns: eight 16×16 px cells confined to the odd 16 px row bands, the two frames offset by one cell so alternating them scrolls sideways. 2,048 bytes of flash to say that is a bad trade.

They're now emitted by the host-tested crossing_pattern unit and drawn with fillRect(). The bird splash is untouched — that's real artwork, not a pattern, and after this it's the only bitmap left in images.h.

Equivalence is proven, not assumed

tests/crossing_pattern_test.cpp pins the original 2 KB as goldens, rasterizes the generated rectangles into a framebuffer, and memcmps all 128×64 pixels of both frames. What shows on the device is unchanged.

Note on how this was applied

Not a straight cherry-pick. display_pages.ino, images.h and CLAUDE.md are CRLF on master and LF on BETA, so git cherry-pick conflicts on the entire file for each of them.

Applied by hand instead:

• images.h — verified byte-identical between master and BETA-pre-change modulo line endings first, then took BETA's post-change content converted back to CRLF.
• display_pages.ino, CLAUDE.md — the individual hunks applied in place, so master keeps its CRLF. (CLAUDE.md needed a different anchor row anyway: master has no sprint_select entry.)
• crossing_pattern.{h,cpp}, tests/crossing_pattern_test.cpp, and the two CMake one-liners came across unchanged.

Diff is 9 files / +339 / −139, with no whole-file line-ending churn.

Test plan

• cmake -S tests -B build && cmake --build build — 271 cases / 4,192 assertions, all pass on master
• The 5 frameRects cases specifically: 5 passed / 167 assertions, including both byte-identical golden comparisons
• No dangling references to image_data_calculating1/2 outside comments and the test goldens
• crossing_pattern.cpp added to both tests/CMakeLists.txt and BirdsEye/sim/CMakeLists.txt (the sim compiles display_pages.ino, so omitting it would be an undefined symbol at link)
• CI: compile-sketch flash delta should show ≈ −2,048 B on both boards

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Generated by Claude Code

[github-actions]

Coverage — host-testable units

📂 Overall coverage

Metric	Coverage
Lines	🟢 799/809 (98.8%)
Functions	🟢 83/83 (100.0%)
Branches	🟢 622/691 (90.0%)

📄 File coverage

File	Lines	Functions	Branches
BirdsEye/camera_fsm.cpp	🟢 222/230 (96.5%)	🟢 20/20 (100.0%)	🟡 126/144 (87.5%)
BirdsEye/crc32.cpp	🟢 30/30 (100.0%)	🟢 4/4 (100.0%)	🟢 24/24 (100.0%)
BirdsEye/crossing_pattern.cpp	🟢 15/15 (100.0%)	🟢 1/1 (100.0%)	🟢 12/12 (100.0%)
BirdsEye/dovex_header.cpp	🟢 100/101 (99.0%)	🟢 6/6 (100.0%)	🔴 61/92 (66.3%)
BirdsEye/filename_validator.cpp	🟢 14/14 (100.0%)	🟢 1/1 (100.0%)	🟢 30/30 (100.0%)
BirdsEye/gps_stats.cpp	🟢 25/25 (100.0%)	🟢 3/3 (100.0%)	🟢 8/8 (100.0%)
BirdsEye/gps_status_page.cpp	🟢 25/25 (100.0%)	🟢 3/3 (100.0%)	🟢 24/24 (100.0%)
BirdsEye/gps_time.cpp	🟢 45/45 (100.0%)	🟢 6/6 (100.0%)	🟢 30/32 (93.8%)
BirdsEye/gps_validation.cpp	🟢 24/24 (100.0%)	🟢 2/2 (100.0%)	🟢 66/66 (100.0%)
BirdsEye/haversine.cpp	🟢 8/8 (100.0%)	🟢 1/1 (100.0%)	⚫ 0/0 (0.0%)
BirdsEye/insta360_protocol.cpp	🟢 140/140 (100.0%)	🟢 16/16 (100.0%)	🟡 86/98 (87.8%)
BirdsEye/lap_format.cpp	🟢 18/18 (100.0%)	🟢 1/1 (100.0%)	🟢 9/9 (100.0%)
BirdsEye/sat_bars.cpp	🟢 33/33 (100.0%)	🟢 2/2 (100.0%)	🟢 51/54 (94.4%)
BirdsEye/sd_access_policy.cpp	🟢 9/9 (100.0%)	🟢 3/3 (100.0%)	🟢 18/18 (100.0%)
BirdsEye/sd_format_page.cpp	🟢 25/25 (100.0%)	🟢 3/3 (100.0%)	🟢 25/26 (96.2%)
BirdsEye/sensoregg_protocol.cpp	🟢 39/40 (97.5%)	🟢 7/7 (100.0%)	🟢 25/26 (96.2%)
BirdsEye/tach_filter.cpp	🟢 15/15 (100.0%)	🟢 3/3 (100.0%)	🟡 7/8 (87.5%)
BirdsEye/wake_cause.cpp	🟢 12/12 (100.0%)	🟢 1/1 (100.0%)	🟢 20/20 (100.0%)