refactor(srt): unify property order, expose resilience knobs on inputs, share defaults

[srperens]

Continues #552 (closed when its branch was renamed for clarity).

Summary

The four SRT-related blocks (efpsrt + mpegtssrt × input + output) had drifted apart over time:

• inputs lacked the resilience knobs (keep-listening, auto-reconnect, wait-for-connection) that outputs already had
• defaults for those knobs were repeated as inline literals across files
• the property display order in the frontend was different across blocks, even for properties that exist in all four

This PR cleans all of that up.

Changes

1. Expose three resilience properties on SRT inputs

On both efpsrt_input and mpegtssrt_input:

• keep_listening (default true) — keep srtsrc alive after peer disconnect so reconnects don't require a flow restart
• auto_reconnect (default true) — auto-reconnect on connection failure
• wait_for_connection (default false) — do NOT block pipeline state on peer presence (upstream srtsrc default is true, but that deadlocks PAUSED→PLAYING when the peer is offline)

Each is gated by srtsrc.has_property(...) for compatibility with older gst-plugins-bad versions that lack the property. keep_listening was already exposed on efpsrt_input but is new on mpegtssrt_input; the other two are new on both.

2. Share boolean defaults via strom-types

Three new constants in types/src/block.rs, matching the existing pattern for DEFAULT_SRT_INPUT_URI etc:

• DEFAULT_SRT_KEEP_LISTENING = true
• DEFAULT_SRT_AUTO_RECONNECT = true
• DEFAULT_SRT_WAIT_FOR_CONNECTION = false

All four SRT blocks (input + output) now reference these constants instead of repeating literal values. No behavior change — previous inline literals matched these values exactly.

3. Unified property display order across all 4 SRT blocks

The frontend renders `exposed_properties` in declared order with no sorting, so the only fix is to keep declaration order consistent across blocks. New unified prefix:

#	All 4 blocks
1	num_video_tracks
2	num_audio_tracks
3	srt_uri
4	latency
5	wait_for_connection
6	auto_reconnect
7	keep_listening (input only — srtsink doesn't expose it)
8	decode (inputs only)

Then block-specific properties follow the prefix:

• `efpsrt_input`: bucket_timeout, hol_timeout, normalize_segment
• `mpegtssrt_input`: tsdemux_latency, ignore_pcr
• `efpsrt`: sync, mtu
• `mpegtssrt`: sync

Previously the inputs had num_video_tracks / num_audio_tracks at the bottom and the new resilience props in the middle, which was inconsistent with the outputs and pushed the track-count properties from "near top" to "near bottom" in the frontend.

Test plan

• `cargo check` clean
• `cargo fmt` clean
• `cargo test --test openapi_test` clean
• Pre-commit (fmt + clippy + secret scan) passes
• Verify on `str` host: SRT input survives peer drop and reconnects without flow restart
• Verify in browser GUI: properties display in the unified order across all 4 SRT blocks

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