[Fi3w0]

Fixes found during the first standalone run on real Nvidia hardware (RTX 3060, proprietary 595.99.02, Gentoo), plus the results of that pass. Stacked on claude/new-session-bppt7l: this PR only contains the 13 commits below.

What changed and why

Behavior fixes

• 2727de9 Client drag and drop works. WaylandDndGrabHandler was an empty impl, so Smithay's default dnd_requested cancelled every drag source immediately. Nothing could be dragged between apps, and Firefox detached every dragged tab into a new window. Drags now start a DnDGrab (pointer and touch); the icon is drawn at the pointer on udev (never over the lock screen), gets frame callbacks, and is cleared on drop/cancel.
• 3286393 Glass shows the wallpaper at the right size on fractional scales. Captures render at scale 1.0 in physical pixels but reused the logical-size wallpaper element, so at 1.25x every capture (frost/water glass, layer glass, shader sources, workspace transitions) drew the wallpaper at 80% size from the top-left.
• 8ebb259 output { } blocks apply on config reload. The wlr-output-management apply path is now a shared apply_output_changes(); reload uses it for transform/scale/position. A different mode or enabled = false still needs a modeset and now shows a notice instead of being ignored.
• 6517964 spawn takes quoted arguments ('...', "...", \ escapes; still no shell expansion; unterminated quotes fall back to the old split). tidectl re-quotes spawn arguments, reads global flags only before the command, and tidectl help prints help.
• e4867b1 IPC requests that end at EOF without a newline are answered (or get the normal invalid request error) instead of being dropped silently.
• 182df1b cursor_hide_after = 0 is accepted as documented.
• 490df73 doctor enumerates /dev/dri and reports render and card nodes separately.
• e2385eb preserves the documented doctor --json and perf --json spellings while still leaving flags after actions such as spawn untouched.

Default change

• c593da7 Automatic attention depth is opt-in (depth { enabled = false } in code and in the generated config).

Docs

• 2830ab7 pointer_modifier row in the settings table (it does not follow @mod); spawn quoting rules.
• 13b104e CHANGELOG entries.
• c41a9a4, ad0ed6b TECHNICAL_REPORT.md / report.md: the Nvidia pass.

How it was verified

• cargo fmt --all -- --check, cargo clippy --locked --all-targets -- -D warnings (with and without --features screencast), cargo test --locked: all green. New regression tests for the depth default, spawn splitting and tidectl quoting, capture wallpaper size, and cursor_hide_after.
• Standalone udev session on the RTX 3060, two outputs (2560x1440@144 at 1.25x, 1920x1080@180 at 1.0x), iGPU excluded with gpu { }:
  • drag and drop Dolphin to Firefox, tab drag out and back in;
  • frost glass on the 1.25x output lines up with the wallpaper (screenshot comparison before/after);
  • swapping the two output positions in the config applied live and back;
  • quoted spawn arrived as a single argument (checked in /proc/<pid>/cmdline);
  • portal screen sharing from native Vesktop worked;
  • doctor all-pass.
• Nested run of the same build: tidectl help, quoted spawn, flags after the command, and EOF/truncated IPC requests.

RAM / perf impact

None on the render path in normal use: the DnD icon only renders during a drag, and the capture wallpaper is the same texture at a different size. Measured on this build (details in report.md): idle ~1% of one core, 131 MiB TideWM VRAM; nine frost windows ~0-1% CPU, 139 MiB. On Nvidia, PSS plateaus near 180 MiB after warm-up, of which ~60-95 MiB is /dev/nvidia* mappings. Open/close cycles return to the same value with a flat heap, so it is not a leak, but the doctor's decorated-tier limit (280 MiB) can be reached on Nvidia.

Still open

• Tearing on the HDMI output only, unchanged at scale 1.0; likely the cable or HDMI bandwidth at 1440p144.
• Firefox PDF text selection improved but still imprecise.
• Layer glass and layer shaders were not exercised (no layer-shell client).