fix: make streaming reasoning-tag filter case-insensitive

The streaming think-tag suppressors in cli.py (_stream_delta) and
gateway/stream_consumer.py (_filter_and_accumulate) matched tag names
with case-sensitive str.find(), so only the exact-case literals in the
tag tuples were caught. Mixed-case variants a model may emit — <Think>,
<ThInK>, <REASONING>, <Thought> — slipped through and leaked raw
reasoning into the user-visible stream.

Match against a lowercased view of the buffer with lowercased tag names
at all three sites (open-tag boundary search, partial-tag hold-back,
close-tag search) in both paths. Only KNOWN tag names are matched — no
substring matching — and the block-boundary gating that protects prose
mentions of <think> is preserved.

- 6 parametrized case-insensitive regression tests in each of
  tests/gateway/test_stream_consumer.py and
  tests/cli/test_stream_delta_think_tag.py.

Salvaged from PR #27289 by @YLChen-007.

scripts/release.py

@@ -45,6 +45,7 @@ ACP_REGISTRY_MANIFEST = REPO_ROOT / "acp_registry" / "agent.json"
 
 # Auto-extracted from noreply emails + manual overrides
 AUTHOR_MAP = {
+    "30854794+YLChen-007@users.noreply.github.com": "YLChen-007",  # PR #27289 salvage (case-insensitive streaming reasoning-tag filter in cli.py _stream_delta + gateway stream_consumer so mixed-case variants like <Think>/<ThInK> are suppressed, not just the hardcoded case literals)
     "259353979+testingbuddies24@users.noreply.github.com": "testingbuddies24",  # PR #43192 salvage (strip orphan think-tag close tags in progressive gateway stream so a bare </think> whose open was dropped upstream can't leak to the user)
     "shx_929@163.com": "Lazymonter",  # PR #42914 salvage (retry launchd bootstrap after bootout on EIO for install/start instead of degrading to detached)
     "5848605+itenev@users.noreply.github.com": "itenev",  # PR #22753 salvage (asyncify model-context resolution in gateway message path so blocking requests.get can't starve Discord heartbeats)