docs: define implementation dependency and milestone plan (#37)

[litroc]

Primary issue: #37

Changes

• provides the complete architecture-to-production dependency graph and explicit architecture: integrate and obtain approval for the architecture package #38 implementation gate;
• maps every confirmed gap to reconcile, extend, replace, validate, justified retain/non-action, or external dependency;
• defines M0–M5 milestones with entry/exit criteria, owners, risks, review points, critical path, and safe parallel sets;
• specifies eleven new implementation issues plus existing deployment: publish Docusaurus to Cloudflare Pages at docs.l-it.io #40 and content: publish Platform Governance & Evidence documentation #115 with scope, exclusions, owner, dependencies, deliverables, acceptance, validation, evidence, labels, type, milestone, and parent;
• prevents duplicate implementation of the current Docusaurus/build/search and public/private baseline;
• defines shared-file sequencing, review checkpoints, rollback/migration needs, and exact approval behavior.

Validation

• git diff --check
• npm run lint
• npm run typecheck
• npm run test:content
• npm run build including Pagefind

All checks pass with Node 24.18.0.

Boundaries

• Planning-only; every implementation issue remains Todo and blocked by architecture: integrate and obtain approval for the architecture package #38.
• This PR creates no implementation branch, configuration, deployment, or production change.

[cloudflare-workers-and-pages]

Deploying lightning-it-documentation with    Cloudflare Pages

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Branch Preview URL:	https://agent-issue-37-implementatio.lightning-it-documentation.pages.dev

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[Copilot]

Pull request overview

Adds a new Architecture planning document that consolidates the architecture-to-implementation dependency graph, milestone sequencing, and a structured breakdown of implementation issues gated by #38, and wires it into the Docusaurus sidebar.

Changes:

• Adds a new /architecture/implementation-plan/ page with a dependency graph, gap disposition mapping, milestones (M0–M5), and issue-level contracts for planned implementation work.
• Registers the new page in the “Architecture” sidebar list.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
sidebars.ts	Adds the new architecture implementation plan doc to the Architecture sidebar navigation.
docs/architecture/implementation-plan.md	Introduces the dependency graph, milestones, and implementation issue breakdown gated by #38.

Comments suppressed due to low confidence (1)

docs/architecture/implementation-plan.md:310

• This PUBLIC planning document names "Confluence" as a destination for updates. To keep the publication boundary tight and avoid referencing internal systems by name, make this generic (e.g. "roadmap update").

- Scope/deliverables: approved page and navigation using shared models,
  production verification, public-safe evidence, roadmap and canonical
  Confluence update only after live acceptance.
- Exclusions: unverified product capabilities, private source content, and
  Confluence updates before production truth.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

docs/architecture/implementation-plan.md:308

• This line contains a duplicated word (“canonical”) due to the previous line already ending with “canonical”. Removing the duplicate avoids an awkward “canonical canonical” phrasing.

  canonical external source update only after live acceptance.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.