docs(diagrams): migrate mermaid docs to plantuml and png

[igorsatsyuk]

Summary

• replace Mermaid diagrams in README with rendered PNG diagrams
• add PlantUML sources under docs/diagrams/*.puml
• add docs/architecture.md as the central architecture-diagrams document
• add docs/diagrams/generate-diagrams.ps1 to regenerate PNG files

Notes

• this follows the same PlantUML + PNG documentation style used in did-idp-jwt-bridge

[Copilot]

Pull request overview

Migrates the project’s architecture/flow documentation from Mermaid-in-README to a PlantUML-source + rendered-PNG approach, and centralizes diagram documentation under docs/architecture.md.

Changes:

• Replaced Mermaid diagrams in README.md with embedded PNGs and links to the corresponding .puml sources.
• Added PlantUML sequence diagram sources under docs/diagrams/*.puml along with rendered PNG outputs.
• Added a PowerShell script to regenerate PNGs and a central docs/architecture.md index for diagrams.

Reviewed changes

Copilot reviewed 8 out of 13 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
README.md	Swaps Mermaid blocks for PNG embeds and points to .puml sources; adds link to central architecture doc.
docs/architecture.md	New central document that embeds PNGs and references the PlantUML sources.
docs/diagrams/generate-diagrams.ps1	Adds a regeneration script to download PlantUML and render all *.puml to PNG.
docs/diagrams/sequence-auth-login.puml	New PlantUML source for login sequence.
docs/diagrams/sequence-auth-refresh.puml	New PlantUML source for refresh sequence.
docs/diagrams/sequence-auth-logout.puml	New PlantUML source for logout sequence.
docs/diagrams/sequence-async-client-create.puml	New PlantUML source for async client creation sequence.
docs/diagrams/sequence-observability-flow.puml	New PlantUML source for observability data-flow sequence.

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[github-actions]

🧪 Test Results

Unit Tests

• Total:
• Passed: 123
• Failed: 0
• Skipped: 1

Integration Tests

• Total:
• Passed: 61
• Failed: 0
• Skipped: 0

[Copilot]

Pull request overview

Copilot reviewed 8 out of 13 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 13 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 14 changed files in this pull request and generated no new comments.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud