[sanohiro]

Adds clockwise display rotation for tablets and portrait panels, with matching logical layout, rendering, framebuffer clears, screenshots, and pointer coordinates. NumLock-off keypad navigation now behaves like dedicated navigation keys. Addresses #17 and #18.

Also completes Kitty image transfers whose final chunk omits m, prevents sibling-file changes from triggering config reloads, supports relative config paths and atomic saves, and makes grayscale font rendering work with the RGB glyph atlas. Absolute pointer coordinates are clamped before rotation.

Includes interactive rendering/pointer/keypad checks, bounded stress tools, shared agent instructions, English/Japanese documentation, and the v1.5.0 version/changelog update.

Validation:

• cargo test --locked: 65 passed, 1 hardware-dependent seatd test ignored.
• cargo test --locked --no-default-features: 65 passed.
• cargo build --release --locked: passed for v1.5.0.
• Shell/Python syntax and both C utilities' strict compiler checks passed.
• The relative-config atomic-save regression failed before the fix and passed afterward.
• Systemd visual smoke screenshots confirmed text, colors, Sixel, Kitty transfers, partial update cleanup, and alternate-screen restoration before the final review fixes. Rotation transforms have unit coverage; all-angle hardware testing and dynamic VT restoration are not claimed.