Add controlled Whisper and LLM benchmark results

Document and preserve the controlled Progeo benchmark series.

Whisper comparison:
- Compare whisper.cpp large-v3 and large-v3-turbo
- Identify and verify BUG-012: extraction stability depends on chunk size
- Repeat both transcription variants with identical reduced chunk budgets
- Select large-v3-turbo as the current production transcription model

LLM comparison:
- Compare qwen3.5:9b with qwen3.5:35B-A3B
- Preserve identical transcript, Meeting Context, prompts and chunking
- Retain qwen3.5:9b as the production recommendation
- Record runtime, repair burden and semantic-quality findings

Current production benchmark configuration:
- whisper.cpp large-v3-turbo
- target_chars=4500
- max_chars=5500
- min_chars=2500
- overlap_blocks=0
- qwen3.5:9b
- num_ctx=32768
- think=false
- temperature=0

BUG-012 remains verified but not yet fixed in the production chunker.

samples/benchmarks/progeo_whisper_turbo_20260805_120903/timings_partial.json

@@ -0,0 +1,17 @@
+{
+  "normalization": {
+    "exit_code": 0,
+    "log": "samples\\benchmarks\\progeo_whisper_turbo_20260805_120903\\normalization_stdout_stderr.txt",
+    "runtime_seconds": 0.788
+  },
+  "chunking": {
+    "exit_code": 0,
+    "log": "samples\\benchmarks\\progeo_whisper_turbo_20260805_120903\\chunking_stdout_stderr.txt",
+    "runtime_seconds": 0.269
+  },
+  "extraction": {
+    "runtime_seconds": 198.349,
+    "exit_code": 1,
+    "log": "samples\\benchmarks\\progeo_whisper_turbo_20260805_120903\\extraction_stdout_stderr.txt"
+  }
+}