Fix dspy task 8635: change min_instr_chars default from 30 to 0 (#40)

The combined.patch adds instruction length bounds with min_instr_chars=30.
The pre-existing test test_propose_instructions_for_program[None] uses
DummyLM which returns "instruction" (11 chars). This falls below the
30-char minimum, causing the code to fall back to the default signature
instruction, breaking the assertion.

tests2.patch corrects this assertion but tests1.patch does not, so
feature 1 tests always fail.

Changing the default to 0 preserves backward compatibility while keeping
the length-bounds feature functional when explicitly configured.

Author: AlienKevin

dataset/dspy_task/task8635/combined.patch

@@ -51,7 +51,7 @@ index 13722b4b..2d60a9b6 100644
          use_tip=True,
          verbose=False,
 +        max_description_chars=2000,
-+        min_instr_chars=30,
++        min_instr_chars=0,
 +        max_instr_chars=600,
 +        rephrase_when_too_long=False,
      ):
@@ -201,7 +201,7 @@ index 13722b4b..2d60a9b6 100644
 +        max_instruct_history=5,
 +        tip_weights=None,
 +        max_description_chars=2000,
-+        min_instr_chars=30,
++        min_instr_chars=0,
 +        max_instr_chars=600,
 +        rephrase_when_too_long=False,
      ):