chore: promote performance & tracing APIs to stable

[jpnurmi]

Promote 68 performance monitoring and tracing functions to stable. (~50% of the experimental API surface!)

These features have shipped incrementally since 2021. None of the features are labeled experimental in the developer docs.

Date	Age	API	Docs
2021‑12‑08	4y 8mo	sentry_options_set_max_spans, sentry_options_get_max_spans	maxSpans
2021‑12‑08	4y 8mo	sentry_options_set_traces_sample_rate, sentry_options_get_traces_sample_rate	tracesSampleRate
2021‑12‑08	4y 8mo	sentry_transaction_finish	New Span and Transaction Classes
2021‑12‑15	4y 8mo	sentry_transaction_set_name	New Span and Transaction Classes
2021‑12‑22	4y 7mo	sentry_envelope_get_transaction
2021‑12‑23	4y 7mo	sentry_transaction_context_set_name	New Span and Transaction Classes
2021‑12‑23	4y 7mo	sentry_transaction_context_set_operation	Span Operations
2021‑12‑23	4y 7mo	sentry_transaction_context_set_sampled, sentry_transaction_context_remove_sampled	Sampling
2021‑12‑23	4y 7mo	sentry_transaction_start	Static API Changes
2022‑01‑07	4y 7mo	sentry_set_span	Scope Changes
2022‑01‑08	4y 7mo	sentry_span_start_child	Explicitly creating a child span
2022‑01‑08	4y 7mo	sentry_span_finish	Span Interface
2022‑01‑11	4y 7mo	sentry_transaction_set_tag, sentry_transaction_remove_tag, sentry_transaction_set_data, sentry_transaction_remove_data
2022‑01‑11	4y 7mo	sentry_span_set_tag, sentry_span_remove_tag, sentry_span_set_data, sentry_span_remove_data	Attributes
2022‑01‑13	4y 7mo	sentry_transaction_context_new, sentry_transaction_start_child	New Span and Transaction Classes
2022‑01‑13	4y 7mo	sentry_span_set_status, sentry_transaction_set_status	Span Interface
2022‑01‑18	4y 7mo	sentry_transaction_context_update_from_header	continueTrace
2022‑01‑18	4y 7mo	sentry_span_iter_headers, sentry_transaction_iter_headers	getTraceData
2022‑01‑24	4y 6mo	sentry_set_transaction_object	Scope Changes
2023‑04‑25	3y 3mo	sentry_transaction_context_new_n, sentry_transaction_context_set_name_n, sentry_transaction_set_name_n	New Span and Transaction Classes
2023‑04‑25	3y 3mo	sentry_transaction_context_set_operation_n	Span Operations
2023‑04‑25	3y 3mo	sentry_transaction_context_update_from_header_n	continueTrace
2023‑04‑25	3y 3mo	sentry_transaction_start_child_n, sentry_span_start_child_n	Explicitly creating a child span
2023‑04‑25	3y 3mo	sentry_transaction_set_tag_n, sentry_transaction_remove_tag_n, sentry_transaction_set_data_n, sentry_transaction_remove_data_n
2023‑04‑25	3y 3mo	sentry_span_set_tag_n, sentry_span_remove_tag_n, sentry_span_set_data_n, sentry_span_remove_data_n	Attributes
2024‑12‑04	1y 8mo	sentry_transaction_start_ts, sentry_transaction_finish_ts, sentry_transaction_start_child_ts, sentry_transaction_start_child_ts_n, sentry_span_start_child_ts, sentry_span_start_child_ts_n, sentry_span_finish_ts	New Span and Transaction Classes
2025‑01‑14	1y 7mo	sentry_options_set_traces_sampler	tracesSampler
2025‑01‑14	1y 7mo	sentry_transaction_context_get_name, sentry_transaction_context_get_operation
2025‑05‑15	1y 3mo	sentry_options_set_before_transaction	Before-Send-Transaction Hook
2025‑07‑01	1y 1mo	sentry_regenerate_trace	startNewTrace
2025‑10‑08	10mo	sentry_options_set_propagate_traceparent, sentry_options_get_propagate_traceparent	propagateTraceparent
2026‑05‑13	3mo	sentry_options_set_org_id, sentry_options_set_org_id_n, sentry_options_set_strict_trace_continuation, sentry_options_get_strict_trace_continuation	Strict Trace Continuation
2026‑07‑17	1mo	sentry_transaction_discard, sentry_span_discard
2026‑08‑13	8d	sentry_scope_set_transaction_object, sentry_scope_set_span	Scope Changes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.64%. Comparing base (8705b5d) to head (8f442c6).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2012      +/-   ##
==========================================
- Coverage   74.66%   74.64%   -0.02%     
==========================================
  Files         104      104              
  Lines       26346    26346              
  Branches     4781     4781              
==========================================
- Hits        19670    19665       -5     
- Misses       5335     5342       +7     
+ Partials     1341     1339       -2     

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