docs: amend constitution to v1.1.0 (Observability for tracing migration)

Principle V now reflects the merged tracing migration (#148):
- tracing + tracing-opentelemetry spans in every build, with OTLP export
  gated on OTLP_OTLS_ENDPOINT;
- no manual Context threading;
- every spawn / fan-out carries its parent span;
- RUST_LOG gates span export (run at info/debug).
Layer and Tech Stack wording matches.

Also corrects stale "release builds only" telemetry notes in CLAUDE.md and
.env.example, updates the CLAUDE.md dependency list, and fixes the README's
RUST_LOG default. It also documents OTLP_OTLS_ENDPOINT in the README, as
Principle IV requires.

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

README.md

@@ -72,7 +72,8 @@ They should be defined where the binary is located or above it in an `.env` file
 - `GIFS_DIRECTORY` is a path where generated video GIF thumbnails should be stored
 - `BIND_URL` is the url and port to bind to (typically your own IP address)
 - `SECRET_KEY` is the *hopefully* random string to sign Tokens with
-- `RUST_LOG` is one of `off, error, warn, info, debug, trace`, from least to most noisy [error is default]
+- `RUST_LOG` is one of `off, error, warn, info, debug, trace`, from least to most noisy [default: `info` for spans, `error` for dev console logs]. It also gates tracing-span export, so keep it at `info` or `debug`
+- `OTLP_OTLS_ENDPOINT` (optional) is an OTLP/gRPC collector URL (e.g. SigNoz, Jaeger) for span export, in any build [default: unset, no export]
 - `EXCLUDED_DIRS` is a comma separated list of directories to exclude from the Memories API
 - `PREVIEW_CLIPS_DIRECTORY` (optional) is a path where generated video preview clips should be stored [default: `preview_clips`]
 - `WATCH_QUICK_INTERVAL_SECONDS` (optional) is the interval in seconds for quick file scans [default: 60]