feat(stream): handles over TA-Lib C 0.8.1's streaming API (#757)

[mario4tier]

Implements #757: talib.stream becomes handles over TA-Lib C 0.8.1's streaming
API, replacing the last-value functions.

from talib import stream

s = stream.RSI(history, timeperiod=14)   # same arguments as talib.RSI
s.value                                  # == talib.RSI(history)[-1], bitwise

for bar in feed:
    emit(s.update(bar))                  # O(1) per closed bar

s.peek(forming)                          # what update would return; commits nothing
fork = s.copy()                          # independent handle at the same bar
s, rsi = stream.RSI.open_and_fill(history, timeperiod=14)   # both in one pass

Multi-output functions answer with a named tuple whose fields are the output
names in the docstring; single-output ones with a bare float (or int).
out_range and advance() carry the C contract's bar range. New
talib.InsufficientHistory for an open with too little history.

What to read

Two files: tools/generate_stream.py (the generator) and
tests/test_stream.py (the suite). talib/_stream.pxi, talib/stream.pyi
and talib/_ta_lib.c are generated output — make generate plus make cython
reproduces them byte for byte, so the 275k-line diff is 1000 lines of review.

Breaking change

talib.stream_X and the value-returning talib.stream.X are gone, as are the
stream_* stubs in _ta_lib.pyi (talib/stream.pyi types the handles
instead). Migrating is stream.X(...) -> stream.X(...).value, and the
compiler will not find the sites: if stream.CDLDOJI(o, h, l, c): used to test
the pattern and now tests a handle, which is always true.

A few decisions worth a second opinion

• Leading NaN bars are skipped, exactly as the Function API's check_begidx
  skips them, so stream.X(h).value == talib.X(h)[-1] holds bitwise. The offset
  is added back to out_range and to the MAXINDEX/MININDEX/MINMAXINDEX
  outputs, which the batch tier also rebases.
• out_range and advance() are exposed although refactor(streaming): replace with the v0.8.1 Core implementation #757 does not name them;
  they are part of the C streaming contract and the other backends have them.
• open_and_fill returns (handle, outputs), outputs being exactly what the
  batch call returns, pandas/polars container included.
• No close() — __dealloc__ frees, as GC suffices for a managed handle.
• .github/workflows/tests.yml gains dev in both branch filters; it
  triggered on master only, so a PR into dev ran no checks at all. If this PR
  shows none, that filter needs to land on dev first.

Verification

• 2100 tests, corpus derived from TA_FUNC_FLG_STREAM: every streaming function
  compared bit-exactly against its batch series over three datasets (real prices,
  prices mapped into [-1, 1], and one with zero-range and zero-volume bars), two
  compatibility modes and two warm-up prefixes, plus a NaN-prefixed corpus.
• test_the_data_discriminates asserts only candlesticks are output-flat, so the
  comparison cannot quietly go vacuous.
• Signature parity against the batch function, which is the only check that
  catches an argument-order slip in MEDPRICE/ADD/MULT/WCLPRICE — those are
  bit-identical under a high/low swap.
• Built and green against ta-lib C dev, including the no-Cython sdist path that
  compiles the committed _ta_lib.c, and a wheel that passes the release test
  command.