feat: short bar mode for timer widgets

[t-benoit]

Summary

SessionUsage and WeeklyUsage already support a "short bar" (slider) display mode via the (p)rogress toggle keybind. The three timer widgets in the Usage category did not — their cycle stopped at medium bar. This PR enables slider modes on all of them:

• BlockTimer
• BlockResetTimer
• WeeklyResetTimer

New cycle for each:

time → long bar (32) → medium bar (16) → short bar (10) → short bar (no %) → time

Visual

Block Timer:
Block: 3hr 45m # time
Block [████████████████░░░░░░░░░░░░░░░░] 50.0% # long bar
Block [████████░░░░░░░░] 50.0% # medium bar
Block ▓▓▓▓▓░░░░░ 50.0% # short bar (new)
Block ▓▓▓▓▓░░░░░ # short bar only (new)

Block Reset Timer / Weekly Reset Timer behave identically (different label).

Notes

• (v)invert fill is now also exposed in slider modes (previously only in progress modes).

Test plan

• bun run lint (tsc + eslint, 0 warnings)
• bun test — 1164 tests pass; ~5–6 new tests per widget covering slider rendering (elapsed, slider-only, inverted), the new invert keybind in slider mode, and the short bar / short bar only modifier text. BlockTimer additionally covers the empty-fallback slider rendering
• Manual TUI check: cycle through all 5 modes via p, toggle v in slider mode, verify hours-only/compact/absolute metadata are stripped on entering bar modes