fix: anchor string patterns in match() to consume full keypath

[gaoflow]

Bug

benedict.match() converts string wildcard patterns to regex and applies
regex.match(), which only verifies a prefix match — the rest of the
keypath is silently ignored.

For a pattern like "*a" the transformation produces (.)*a. Because
regex.match("ab") anchors at the start but not the end, it succeeds on
"ab" (. consumes "a", a matches the first character, "b" is
left unconsumed). The result: keys that do not end in "a" are
erroneously returned.

from benedict import benedict

d = benedict({"aa": 1, "ab": 2, "ba": 3, "bb": 4})
d.match("*a")
# Before fix: [1, 2, 3]   ← "ab" wrongly included
# After fix:  [1, 3]      ← only "aa" and "ba"

Fix

Append "$" to string-derived patterns before compiling so the full
keypath must be consumed. Raw compiled-regex patterns (re.Pattern)
are unaffected and continue to use regex.match() as before.

Tests

Added test_match_with_suffix_wildcard to tests/core/test_match.py;
all 261 existing core + keypath tests continue to pass.