fix(metadata): roll deleted partitions and topics out of parent stats

[numinnex]

Update the Stats from metadata layer when partitions get removed.

[hubcio]

please add integration test (either enhance current one if it exists or create new one)

[codecov]

Codecov Report

❌ Patch coverage is 97.76995% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.02%. Comparing base (6c07954) to head (501881c).

Files with missing lines	Patch %	Lines
core/common/src/types/streaming_stats.rs	93.70%	8 Missing ⚠️
core/server/src/partition_reconciler.rs	95.34%	6 Missing ⚠️
core/partitions/src/iggy_partition.rs	93.84%	4 Missing ⚠️
core/server/src/http/metrics.rs	94.73%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #4046      +/-   ##
============================================
- Coverage     85.98%   85.02%   -0.96%     
  Complexity     1431     1431              
============================================
  Files          1247     1247              
  Lines        192967   188086    -4881     
  Branches     158323   153443    -4880     
============================================
- Hits         165915   159920    -5995     
- Misses        22963    23857     +894     
- Partials       4089     4309     +220     

Components	Coverage Δ
Rust Core	85.72% <97.76%> (-1.17%)	⬇️
Java SDK	67.52% <ø> (ø)
C# SDK	77.08% <ø> (+0.01%)	⬆️
Python SDK	91.31% <ø> (ø)
PHP SDK	85.65% <ø> (ø)
Node SDK	96.26% <ø> (+0.02%)	⬆️
Go SDK	69.43% <ø> (+0.06%)	⬆️

Files with missing lines	Coverage Δ
core/metadata/src/stm/stream.rs	92.89% <100.00%> (+1.27%)	⬆️
core/server/src/boot/mod.rs	87.32% <ø> (-0.14%)	⬇️
core/server/src/boot/recovery.rs	95.46% <100.00%> (ø)
core/server/src/responses.rs	92.14% <100.00%> (+0.03%)	⬆️
core/shard/src/lib.rs	83.82% <100.00%> (-0.13%)	⬇️
core/server/src/http/metrics.rs	96.62% <94.73%> (-0.28%)	⬇️
core/partitions/src/iggy_partition.rs	91.82% <93.84%> (+0.09%)	⬆️
core/server/src/partition_reconciler.rs	98.00% <95.34%> (-0.08%)	⬇️
core/common/src/types/streaming_stats.rs	91.83% <93.70%> (+1.17%)	⬆️

... and 139 files with indirect coverage changes

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[hubcio]

one finding sits outside the diff, so it goes here.

core/shard/src/lib.rs:8180 - fence_partition_for_rebuild tombstones and enqueues ConfirmRemove without settling the partition counters. metadata never deleted the partition, so the registry entry survives and the rebuild's get-or-create hands back the fenced incarnation's numbers, still sitting in the parent totals. build_partition_fresh only zeroes on its error path, so journal repair then counts the same data twice.

the second exit at :8160-8178, where quarantine fails, never enqueues ConfirmRemove at all, so a settle in that arm would not reach it. both arms need one.

this path predates the pr, but the invariant it breaks is the one this pr establishes.

[numinnex]

/ready

[hubcio]

retain_from_snapshot (stream.rs:722) evicts a partition entry without zeroing its stats, so the still-mounted stale incarnation's later ConfirmRemove takes those bytes a second time out of live siblings. No clamp fires, so nothing surfaces it. Reachable on a donor delete-then-recreate installed ahead of the receiver's frontier. Breaks the invariant at stream.rs:738, and created_revision has no test.

On unchanged lines, so no inline comment:

• boot/recovery.rs:184 points at the zeroing loop this change deleted from boot/mod.rs. Retarget at Streams::from_snapshot.
• streaming_stats.rs:313-326 and :469-482: zero_out_* cascades unconditionally, so the new settle runs an amount-0 rollback per deleted partition. if prev == 0 { return; } after each swap.
• Nine public iggy_common return types change from (). A major break with no semver gate - worth a release note.

[numinnex]

/ready