headless ant/term ↗

fix: declare bel/rep/tbc -- audited terminfo against 5 real terminals Systematically compared this file's declared capability set against xterm-256color, foot, alacritty, kitty, and st-256color (compiling both sides with tic + infocmp for a fair, normalized comparison) to find any other implemented-but-undeclared gaps in the same shape as bce/cr. Found three: - bel: feed_ground's BEL case is a deliberate no-op (no bell support in v1), but that's not a reason to leave it undeclared -- sending it is a real, harmless, correctly-handled action, the same structurally-correct-but-static tradeoff already made for blink. Every reference terminal checked declares it. - rep: run_csi's 'b' case (REP) has repeated the last graphic character since early in this project; never declared. - tbc: run_csi's 'g' case handles TBC mode 3 (clear all tab stops) via clear_all_tab_stops; never declared. A stale test comment had conflated this with the genuinely-unimplemented modes 1/2 and asserted tbc should stay absent -- corrected. Also checked for the reverse direction (declared capabilities the code doesn't back) and found none. Genuinely unimplemented features turned up too (CBT/back-tab, the Insert key, shifted special keys, modified function keys) -- left undeclared correctly, since there's no behavior for them to under-promise. Adds bce/cr-style behavior-linking tests for rep and tbc so these can't silently drift stale again either.