fix(orchestrator): S1 fit, rename once, Deutschlandfunk e2e, squelch, tree cause

Requirement 001 phase 6, S1:

- Fit: Agents and Artifacts in a graph view fill the window from 861 px
  up (body.fit flex column); the e2e walk probes #agents/orbit at every
  width for a page no taller than the window.
- Rename once: a session seen under two names by one source (two claims)
  flipped its name on every state build, so the Stream logged a rename
  each poll. Names.observe keeps only the newest sighting per session
  and source, and the timeline emits each (session, before, after) pair
  once.
- Deutschlandfunk: root cause was the signed media-src, which never
  listed the redirect target f111.rndfnk.com that st01.sslstream.dlf.de
  answers with (fixed in ba97f7c). The e2e now replays that chain, a
  302 from one https origin to a second, in Chromium and Firefox, with
  self-signed throwaway certificates the drivers accept.
- Squelch: a settings slider 0..1 scales every tone; at 0 no beep plays,
  music on or off (Voice.beep skips a silent tone). Stored settings
  without the key load with 1.0.
- Tree: the missing tree file error names `pkgmgr branch tree` and the
  release and install step that makes the timer write it.

Evidence: make test 655 OK, ruff and markdownlint clean
(/tmp/s1-make-test-1.log); e2e 17 OK, none skipped (/tmp/s1-e2e-3.log);
MEDUSA 14 files, 0 findings.

🎯 Fix: 94 %
💥 Break: 4 %
💸 Cost: 100 %
⏱️ Time: –
🛡️ Security: 100 %
🏆 Score: 90
🚦 Gate: ✅ 90/5, cost and time <= 100, security 100 %

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

orchestrator/kvb_orchestrator/settings.py

@@ -36,6 +36,7 @@ SETTINGS = {
         "direct": {"on": True, "volume": 0.5},
         "radio": {"on": False, "volume": 0.25},
     },
+    "squelch": 1.0,
     "notify": True,
     "streams": [],
     "speech": {"on": False, "classes": ["mayday", "pan-pan", "security"], "muted": []},
@@ -195,6 +196,7 @@ def valid_settings(raw: object) -> dict:
         "colors": {key: color(colors[key], f"colors.{key}") for key in SETTINGS["colors"]},
         "music": {"on": flag(music["on"], "music.on"), "volume": number_in(music["volume"], "music.volume", 0.0, 1.0)},
         "sounds": {kind_name: tone_setting(sounds[kind_name], kind_name) for kind_name in TONES},
+        "squelch": number_in(data["squelch"], "squelch", 0.0, 1.0),
         "notify": flag(data["notify"], "notify"),
         "streams": [stream_entry(entry, index) for index, entry in enumerate(data["streams"])],
         "speech": speech_setting(data["speech"]),