feat: bring SolidSyslog into the build, nothing wired yet

[DavidCozens]

Pull request

What this stage adds

SolidSyslog enters the CMake build and its lwIP adapter pack compiles against our lwipopts.h, but
no application code calls into either yet. --gc-sections strips all of it, so the cost above the
frozen baseline is 0 bytes on every axis — flash, RAM, heap and both task stacks.

That zero is the point: linking a platform pack you do not call is free, and the measurement is
honest enough to show it.

Checklist

• The diff is build-system only — this is deliberately the commit where SolidSyslog enters
  the build, kept apart from any wiring step so a non-CMake integrator can discard it whole.
  (The template's "application-only" wording does not fit this one stage; noted rather than
  ticked falsely.)
• measurements/linked.csv committed, and a row added to measurements/stages.tsv.
• README regenerated: python3 scripts/gen-cost-table.py.
• ./run.sh green (build + QEMU + baseline self-check) — run-report.md committed.

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Context for review: this is 1 of 21 sequential single-commit PRs replaying the integration on
top of the Baseline root. Each lands green and reviewed before the next is built on it, because a
change to an early commit would force every commit above it to be re-run and re-measured.

Summary by CodeRabbit

• New Features

  • Added SolidSyslog with lwIP raw-mode support to the firmware build.
  • Confirmed the linked stage adds no flash or RAM overhead.

• Documentation

  • Updated build-stage descriptions and cost tables to reflect the linked configuration.
  • Revised run metrics and self-check references, with validation remaining successful.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 58280a0f-8374-4ef8-9809-8b245697b3e2

📥 Commits

Reviewing files that changed from the base of the PR and between 9a071e6 and 7d3ccd2.

⛔ Files ignored due to path filters (2)

• measurements/linked.csv is excluded by !**/*.csv
• measurements/stages.tsv is excluded by !**/*.tsv

📒 Files selected for processing (3)

• CMakeLists.txt
• README.md
• run-report.md

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📝 Walkthrough

Walkthrough

The build now fetches and links SolidSyslog with the LwipRaw backend. README.md and run-report.md update the linked-stage description, cost table, mbedTLS measurements, and self-check references.

Changes

SolidSyslog linking and measurements

Layer / File(s)	Summary
SolidSyslog build integration CMakeLists.txt	CMake fetches a pinned SolidSyslog revision, selects LwipRaw, and links SolidSyslog and SolidSyslog::LwipRaw to baseline.
Linked-stage reporting README.md, run-report.md	Documentation changes the stage from Baseline to Linked and updates flash, RAM, mbedTLS metrics, and self-check values.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• cososo-ltd/solid-syslog-example#10: Updates the same SolidSyslog CMake fetch, platform selection, and baseline linking.
• cososo-ltd/solid-syslog-example#26: Adds measurement support related to the updated mbedTLS reporting.
• cososo-ltd/solid-syslog-example#15: Uses the LwipRaw SolidSyslog backend that this build configuration links.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: adding SolidSyslog to the build without wiring it into the app yet.
Description check	✅ Passed	The description matches the template, includes the required stage summary and checklist, and is mostly complete.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch stage/linked

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