Fix shadowed "тңг." currency symbol dropping its trailing dot

[Sanjays2402]

Problem

Price.fromstring("1000 тңг.") returns currency="тңг" (Kazakhstani tenge
without its trailing dot) instead of currency="тңг.", silently dropping the
period that is part of the symbol as it appears in the text.

>>> from price_parser import Price
>>> Price.fromstring("1000 тңг.").currency
'тңг'          # expected 'тңг.'

For comparison, the other dotted national abbreviations behave correctly:

input	currency (before)	currency (after)
1000 тңг.	'тңг' ❌	'тңг.' ✅
1000 руб.	'руб.'	'руб.'
1000 грн.	'грн.'	'грн.'
1000 лв.	'лв.'	'лв.'
1000 тңг (no dot)	'тңг'	'тңг'

Root cause

SAFE_CURRENCY_SYMBOLS is turned into an ordered regex alternation by
or_regex() ("|".join(...)). In an ordered alternation the first matching
branch wins, so when a shorter symbol is a prefix of a longer one and is listed
first, the longer one becomes unreachable.

"тңг" was listed before "тңг.":

    "р.",
    "тңг",     # <- shorter form matches first
    "тңг.",    # <- unreachable: the dot is never captured
    "ман.",

"тңг" is the only dotted/undotted pair in the wrong order. Every sibling
(руб./руб, грн./грн, лв./лв) already lists the dotted form first, so
those symbols keep their dot. The comment at the top of the list even notes that
longer variants "need to be before" shorter ones.

Fix

Swap the two entries so the dotted form comes first, matching the existing
convention for руб., грн., and лв.. This makes the previously dead
"тңг." entry effective without affecting the dot-less "тңг" form.

     "р.",
-    "тңг",
     "тңг.",
+    "тңг",
     "ман.",

+2/−1 in price_parser/parser.py (one swap), +4 in the test file.

Testing

Added a regression example to PRICE_PARSING_EXAMPLES_BUGS_CAUGHT
(the list documented for "bugs we've found in a wild"):

Example(None, "1000 тңг.", "тңг.", "1000", 1000),

Proof it guards the bug (source fix stashed, test kept):

# without the fix:
E   assert Price(amount=Decimal('1000'), currency='тңг') == Example(..., currency='тңг.')
FAILED tests/test_price_parsing.py::test_parsing[None, '1000 тңг.']

# with the fix:
1 passed

Full suite after the fix: 1060 passed, 134 xfailed (was 1059 passed +
the 1 new case, no regressions). ruff check and ruff format --check are
clean on both changed files.

This pull request was prepared with the assistance of AI, under my direction
and review.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.23%. Comparing base (64e213a) to head (72a5fd3).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #80   +/-   ##
=======================================
  Coverage   98.23%   98.23%           
=======================================
  Files           3        3           
  Lines         113      113           
  Branches       16       16           
=======================================
  Hits          111      111           
  Misses          1        1           
  Partials        1        1           

Files with missing lines	Coverage Δ
price_parser/parser.py	97.67% <ø> (ø)

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