Implement more Vim motions and shortcuts (`f`, `t` etc)

Claude Code is currently missing some very useful Vim movements and other Vim shortcuts. Everyone has their favourites, and you probably can't implement them all.

These ones here would make is significantly faster to move the cursor around:

• [x] f / F for jumping to next/prev character in a line ✅
• [x] t / T for jumping to just before next/prev character in a line ✅
• [x] ; and , to repeat previous f/F movement forward / backward
• ; and , to repeat previous t/T movement forward / backward

• [x] (and combined with d / c etc make editing a lot easier)

Some more that would be really useful for editing:

• [x] ciw ✅, yiw, diw ✅ etc for operating on 'inner word's
• [x] yanking text with any of the yank motions (Y, yy, yiw, yf{letter}, etc)
• [x] pasting with p or P in normal mode. Currently it seems you have to enter insert mode to paste with Cmd-V

Some others which would also be handy:

• [x] u ✅ for undo!
• [x] >> / << indent current line
• [x] hJ for joining lines separated by space is handy

Some bugs that I'm aware of that are really annoying:

• BUG: dw deletes too far, it's not meant to delete the trailing newline character on the line
• BUG: a at the very end of a line does not work properly. Cursor ends up in the wrong position

Anyway, thanks so much for adding a Vim mode, it's a great feature. Creating and editing prompts is one of the bottlenecks now! The easier it is to do that the better IMO.

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UPDATE: have been marking off some of these as they have been recently implemented.