fix: retire kitty ctrl+v interception (XWayland breaks router tmux detection)

[NagyVikt]

Why

PR #1 widened the daemon dedup window to 2.5s and fixed the router's socket resolution — but double-pastes persisted. Root cause found today: the kitty→XWayland switch breaks the router's entire detection premise. kitten @ ls reports is_focused=false for every OS window and empty foreground_processes, so focused_window_is_tmux() can never return true. Every Ctrl+V in kitty took the slow fallthrough (background launch spawn, seconds late under load), and the late second fire landed outside any reasonable dedup window — the journal shows identical 162-byte text pastes 4s apart (pane %23 at 15:14:50 and 15:14:54).

What

• config/keybindings.canonical: kitty ctrl+v → UNBOUND — kitty must NOT intercept Ctrl+V. tmux's bind -n C-v becomes the single handler: ~5ms via flashpaste-trigger, and the pane id comes from the pressing client (also killing the wrong-pane hazard of the router's target-less tmux display-message). Non-tmux kitty windows: the raw 0x16 reaches Claude Code, which reads the clipboard itself via the wl-paste shim; plain shells use kitty-native ctrl+shift+v.
• bin/flashpaste-keybindings-check.sh: new UNBOUND keyword — asserts a key must not be bound on a surface (checker previously only supported positive substring rules).
• bin/kitty-paste-router.sh: retired-status header + tracing to the shared clipboard-pipeline log (it was the only paste path that wrote no logs — which is why this regression was invisible).
• tests/keybindings-check.test.sh: covers UNBOUND pass/violation, keeps positive-rule and literal-+ coverage via fixture canonicals.

Test plan

• bash tests/keybindings-check.test.sh — 6/6 pass
• bash tests/kitty-focused-is-tmux.test.sh, tests/wl-paste-guard.test.sh — pass
• bash bin/flashpaste-keybindings-check.sh against live configs — consistent
• Live: ctrl+v map removed from kitty.conf + kitten @ load-config reload; tmux-bind path verified single-paste end-to-end (sentinel via kitten @ send-key → one daemon request, one paste, 38 bytes)
• Real-keypress Ctrl+V verification by user (synthetic XTEST keys don't reach kitty's keymap)

🤖 Generated with Claude Code

[NagyVikt]

AI review (independent fresh-context agent): APPROVE — 0 CRITICAL, 0 HIGH, 0 MEDIUM, 3 LOW.

• UNBOUND keyword logic verified: surface-dispatch → UNBOUND check → continue flow is correct; literal + escaping covered by tests.
• clog tracing guard matches the established pipeline pattern; no set -u traps; no injection surface (quoted args to a printf >> logger).
• Tests 6/6 pass; bash -n clean; manual shellcheck analysis of new lines against the CI gate (-S warning -e SC1090,SC2034,SC2155) finds no new warnings.

LOW (non-blocking): missing-conf file silently satisfies UNBOUND (pre-existing gap shared with positive rules); pre-existing hardcoded paste_image.sh default path; no fixture for UNBOUND-with-absent-conf. Full artifact: .claude/reviews/pr-2-review.md.