fix: keyword scope detection never matched (broken Lua pattern alternation)

[nemanjamalesija]

Summary

Fixes #15.

looks_like_scope_opener and looks_like_scope_closer in paste.lua used | alternation inside Lua patterns — but Lua patterns don't support alternation, so those patterns only matched the literal strings then|do|else|elseif|repeat|function and end|elif|else|elseif|catch|finally. Keyword-based scope detection has never fired.

Brace languages were mostly unaffected because {/}/(/: are caught by character classes, which is why existing tests never surfaced it. But in the issue's scenario — dd a python if-block body, then [p with the cursor on the elif line — the elif was not recognized as a scope closer, so resolve_linewise_target_indent never consulted the previous line and returned the elif's own indent instead of hitting the existing empty-block branch (closer preceded by opener at same indent → current_indent + shiftwidth). The line pasted at column 0, which is a syntax error position in Python:

if foo:
bar()          ← pasted here; should be indented into the if body
elif baz:
    blah()

The same bug silently broke keyword openers/closers everywhere: Lua then/do/end, Ruby end, catch/finally, else.

Fix

Test each keyword with its own pattern instead of one alternation pattern. Behavior is exactly what the surrounding code already intended; no policy change.

Also drops the personal editor context file entry from .gitignore (kept ignored locally via .git/info/exclude instead).

Tests

Two regression tests added (both fail on main, pass with the fix):

• [p above a python elif indents into the if block (the exact issue Bad indentation in Python if/else blocks? #15 scenario)
• ]p below a lua if x then opener indents into the empty block

Full suite: 64/64 passing.