GeezerVison

StartActivity() returns null when no listeners are interested in the
activity. The code accessed activity.IsAllDataRequested without a null
check, causing a NullReferenceException. Use the Npgsql-style pattern
'activity is not { IsAllDataRequested: true }' for early return.

Stopwatch ticks are not TimeSpan ticks when Stopwatch.IsHighResolution
is true (most systems). TimeSpan.FromTicks(stopwatchTicks) produces
incorrect durations. Use Stopwatch.GetElapsedTime() which correctly
handles the frequency conversion.

The semantic conventions renamed db.system to db.system.name. The
well-known value for Firebird is 'firebirdsql', not 'firebird'.
Updated in both FbActivitySource (spans) and FbConnection (metrics).

The semantic conventions mark db.namespace as Conditionally Required
when available. The connection's Database property is used as the value.

The semantic conventions mark error.type as Conditionally Required on
failure. For FbException, use the SQLSTATE code; for other exceptions,
use the full exception type name.

Per OTel semantic conventions, db.query.text and db.query.parameter.*
are Opt-In level attributes that may expose sensitive data. They should
not be collected by default. Added IsQueryTextTracingEnabled flag and
reuse IsParameterLoggingEnabled for parameter tracing.

Replace hardcoded '1.0.0' version with the assembly's informational
version, keeping the telemetry version in sync with the NuGet package.

…ecording

TraceCommandException now records metrics immediately and resets
_startedAtTicks so the later TraceCommandStop (called during Release)
does not record a second, inflated duration that includes cleanup time.

- Remove db.transaction_id custom tag (not in OTel spec, causes server
  round-trip per traced command)
- Remove commented-out db.snapshot_id code
- Remove deprecated exception.escaped attribute
- Remove NormalizeDbNull helper, inline DBNull check

- Set server.port on spans when using a non-default port
- Set db.stored_procedure.name for StoredProcedure command types
- Fix server.address in MetricsConnectionAttributes to not concatenate
  the port (server.port is now a separate attribute)
- Clean up leftover placeholder comments

Set db.query.summary as the low-cardinality activity name on all spans.
For Text commands, extract the first SQL verb (SELECT, INSERT, etc.)
and use it as db.operation.name and in the activity name.

Debug.Assert checks that TraceCommandStart was called before the stop
or exception path, helping catch lifecycle bugs during development.

Prevents potential NullReferenceException if metrics are recorded
before the connection string is set.

Change GetMetrics() to return IEnumerable of tuples via Select instead
of allocating a Dictionary via ToDictionary on every collection cycle.
Also simplify GetConnectionMax to use Select instead of SelectMany.

Suggest default histogram bucket boundaries for operation duration and
connection create time histograms, improving out-of-the-box resolution.
Guarded by NET9_0_OR_GREATER since InstrumentAdvice is a .NET 9 API.

Expose the telemetry source names as public constants so consumers can
easily subscribe: builder.AddSource(FbTelemetry.ActivitySourceName) and
builder.AddMeter(FbTelemetry.MeterName). Internal code updated to use
the constants.

Document the ActivitySource and Meter names, available span attributes,
opt-in sensitive attributes, and available metrics with their types and
semantic convention references.

- Rename project 'Perf' to 'FirebirdSql.Data.FirebirdClient.Benchmarks'.
- Update project to use .net8.
- Upgrade BenchmarkDotNet to version 0.14.0.
- Update baseline nuget package to v10.3.1.
- Add /BenchmarkDotNet.Artifacts to .gitignore.
- Pass command-line arguments to BenchmarkDotNet engine.
- Apply SQL Formatting. Use raw strings.
- Add script run-benchmark.ps1.

…tection

CommandBenchmark (the default suite) only covered BIGINT and VARCHAR UTF8, so
the fixed-length CHAR(n) UTF8 rune path was untested -- the exact path where
issue FirebirdSQL#1272 (~11.7x allocation regression) lives. That regression surfaced only
via the opt-in LargeFetchBenchmark.

- CommandBenchmark: add "CHAR(100) CHARACTER SET UTF8" param; add SampleValue()
  so Execute sends a column-sized string (exercising the write/validate rune
  count path) instead of a bare int.
- docs/benchmark.md: correct the NuGet baseline description (pinned version plus
  a bump-per-release note), add an "Interpreting results" section noting that
  Alloc Ratio is the primary regression signal (with FirebirdSQL#1272 as a worked example),
  and list the third data type.

Verified locally against the released baseline: CHAR UTF8 Fetch Alloc Ratio
~9.6x and Execute ~1.9x, while BIGINT and VARCHAR stay ~1.0.