router: add port-based routing groups

[YangKeao]

What problem does this PR solve?

Issue Number: close #1100

• docs: add cluster-scoped multi-cluster runtime design #1102
• config: add backend cluster schema and multi-port listener config #1103
• backendcluster: add cluster manager and cluster-scoped topology runtime #1104
• metricsreader: move cluster-scoped metrics lifecycle into backend clusters #1105
• router: add port-based routing groups #1106 <-
• backendcluster: route PD and backend traffic through cluster DNS #1107

Add port-based routing to the score-based router.

This PR introduces:

• routing-rule = "port"
• routing by the SQL listener port
• cluster-scoped port groups
• cross-cluster port-conflict detection and blocking

What is changed and how it works:

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Notable changes

• Has configuration change
• Has HTTP API interfaces change
• Has tiproxyctl change
• Other user behavior changes

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 73.96694% with 189 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@ca24d03). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
pkg/manager/backendcluster/manager.go	64.31%	68 Missing and 18 partials ⚠️
pkg/manager/backendcluster/metrics_querier.go	65.51%	27 Missing and 3 partials ⚠️
lib/config/proxy.go	83.33%	15 Missing and 6 partials ⚠️
pkg/balance/router/port_conflict_detector.go	67.74%	7 Missing and 3 partials ⚠️
pkg/proxy/backend/backend_conn_mgr.go	38.46%	6 Missing and 2 partials ⚠️
pkg/server/server.go	61.11%	6 Missing and 1 partial ⚠️
pkg/balance/observer/health_check.go	44.44%	4 Missing and 1 partial ⚠️
pkg/balance/router/group.go	66.66%	5 Missing ⚠️
pkg/balance/router/router_score.go	95.69%	3 Missing and 1 partial ⚠️
pkg/balance/metricsreader/metrics_reader.go	78.57%	3 Missing ⚠️
... and 5 more

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1106   +/-   ##
=======================================
  Coverage        ?   67.21%           
=======================================
  Files           ?      145           
  Lines           ?    15259           
  Branches        ?        0           
=======================================
  Hits            ?    10256           
  Misses          ?     4303           
  Partials        ?      700           

Flag	Coverage Δ
unit	67.21% <73.96%> (?)

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[YangKeao]

/test all

[YangKeao]

/test all

[ti-chi-bot]

@YangKeao: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-unit-test	76c923a	link	true	/test pull-unit-test
pull-mysql-connector-test	76c923a	link	true	/test mysql-connector-test

Full PR test history. Your PR dashboard.

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